drm/imagination: Implement firmware infrastructure and META FW support

The infrastructure includes parsing of the firmware image, initialising
FW-side structures, handling the kernel and firmware command
ringbuffers and starting & stopping the firmware processor.

This patch also adds the necessary support code for the META firmware
processor.

Changes since v8:
- Fix documentation for pvr_fwccb_process()
- Corrected license identifiers

Changes since v6:
- Add a minimum retry count to pvr_kccb_reserve_slot_sync()

Changes since v5:
- Add workaround for BRN 71242
- Attempt to recover GPU on MMU flush command failure

Changes since v4:
- Remove use of drm_gem_shmem_get_pages()
- Remove interrupt resource name

Changes since v3:
- Hard reset FW processor on watchdog timeout
- Switch to threaded IRQ
- Rework FW object creation/initialisation to aid hard reset
- Added MODULE_FIRMWARE()
- Use drm_dev_{enter,exit}

Signed-off-by: Sarah Walker <sarah.walker@imgtec.com>
Signed-off-by: Donald Robson <donald.robson@imgtec.com>
Link: https://lore.kernel.org/r/bb52a8dc84f296b37dc6668dfe8fbaf2ba551139.1700668843.git.donald.robson@imgtec.com
Signed-off-by: Maxime Ripard <mripard@kernel.org>

drm/imagination: Implement power management

Add power management to the driver, using runtime pm. The power off
sequence depends on firmware commands which are not implemented in this
patch.

Changes since v8:
- Corrected license identifiers

Changes since v5:
- Use RUNTIME_PM_OPS() to declare PM callbacks
- Add Kconfig dependency on CONFIG_PM

Changes since v4:
- Suspend runtime PM before unplugging device on rmmod

Changes since v3:
- Don't power device when calling pvr_device_gpu_fini()
- Documentation for pvr_dev->lost has been improved
- pvr_power_init() renamed to pvr_watchdog_init()
- Use drm_dev_{enter,exit}

Changes since v2:
- Use runtime PM
- Implement watchdog

Signed-off-by: Sarah Walker <sarah.walker@imgtec.com>
Signed-off-by: Donald Robson <donald.robson@imgtec.com>
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Link: https://lore.kernel.org/r/e09af4ef1ff514e1d6d7f97c7c5032c643c56f9c.1700668843.git.donald.robson@imgtec.com
Signed-off-by: Maxime Ripard <mripard@kernel.org>