drivers/vesa: fix for RISC-V

* Make ISA bus optional in vesa driver

Change-Id: I1f38f92d81fbfe47224893e1d9dbf6a74306e2f0
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3986
Reviewed-by: Alex von Gluck IV <kallisti5@unixzen.com>

drivers/vesa: Don't dereference frame_buffer when NULL

* Solves the KDL side of #14905
* We do it quietly since we don't want a log event every blit

Change-Id: I8e9b55fab78bd1742a4282dd0812823f33dd9f32

* Added VESA capabilities field to the kernel args.
* The vesa driver no longer uses VGA programming if the chip does not support
VGA compatibility.
* The VESA driver now tries to set the DAC to 8 bits per color gun.
* In VESA modes, the driver no longer tries to use VGA programming; introduced
the new vesa_set_indexed_colors() that is now used for palette programming.
This should fix wrong colors of 8 bit BWindowScreen users with VESA on real
hardware (emulators usually didn't mind either way).
* Note that the app_server needs to maintain a palette per 8 bit screen, as
right now, the colors are garbled after a workspace switch. Stefano, are you
looking into that already?


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@32347 a95241bf-73f2-0310-859d-f6bbb57e9c96

* Moved VGA planar mode blitting into the VESA kernel driver.
* In grayscale mode, the AccelerantHWInterface now sets the palette correctly.
* HWInterface now has a fVGADevice set by AccelerantHWInterface which will be used
to talk to the VESA driver.
* Completed planar blitting for all 4 planes; we now have a perfect 16 color
grayscale mode when you choose "Standard VGA mode" in the boot loader with
an unsupported graphics card (such as in Qemu).


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@19567 a95241bf-73f2-0310-859d-f6bbb57e9c96

* Added VESA capabilities field to the kernel args.
* The vesa driver no longer uses VGA programming if the chip does not support
VGA compatibility.
* The VESA driver now tries to set the DAC to 8 bits per color gun.
* In VESA modes, the driver no longer tries to use VGA programming; introduced
the new vesa_set_indexed_colors() that is now used for palette programming.
This should fix wrong colors of 8 bit BWindowScreen users with VESA on real
hardware (emulators usually didn't mind either way).
* Note that the app_server needs to maintain a palette per 8 bit screen, as
right now, the colors are garbled after a workspace switch. Stefano, are you
looking into that already?


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@32347 a95241bf-73f2-0310-859d-f6bbb57e9c96

* Moved VGA planar mode blitting into the VESA kernel driver.
* In grayscale mode, the AccelerantHWInterface now sets the palette correctly.
* HWInterface now has a fVGADevice set by AccelerantHWInterface which will be used
to talk to the VESA driver.
* Completed planar blitting for all 4 planes; we now have a perfect 16 color
grayscale mode when you choose "Standard VGA mode" in the boot loader with
an unsupported graphics card (such as in Qemu).


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@19567 a95241bf-73f2-0310-859d-f6bbb57e9c96