MFC r328864 (Synaptics part only):

psm(4): Fix panic occuring soon after PS/2 packet has been rejected by
synaptics sanity checker.

After packet has been rejected contents of packet buffer is not cleared
with setting of inputbytes counter to 0. So when this packet buffer is
filled again being an element of circular queue, new data appends to old
data rather than overwrites it. This leads to packet buffer overflow
after 10 rounds.

Fix it with setting of packet's inputbytes counter to 0 after rejection.

While here add extra logging of rejected packets.

PR: 222667 (for reference)
Reported by: Neel Chauhan <neel@neelc.org>
Tested by: Neel Chauhan <neel@neelc.org>

psm: Log syncmask[1], not syncmask[0] twice

MFC of: r328208

MFC r281704:
Synaptics: don't report the middle button when clickPad is used.

MFC r281441:
Add support for controlling the trackpoint when Synaptics is enabled.

MFC r281440:

Improve Synaptics support for newer touchpads.

Enable two finger scrolling by default and disable the edge scrolling if
the touchpad has no physical zone for it. Disable directional scrolling
by default to avoid using extended buttons as scroll buttons.

Add support for ClickPad. On Lenovo laptops, this is the button
reported when one presses the touchpad.

While there, fix a problem where the extended buttons were not reporting
the button release event correctly: we need to save the state of the
buttons and report it to sysmouse until we receive a packet from the
touchpad indicating the button has been released. This makes it
possible to use an extended button to resize a window. On Lenovo
laptops, the major buttons are actually reported as extended buttons.

MFC r281704:
Synaptics: don't report the middle button when clickPad is used.

MFC r281441:
Add support for controlling the trackpoint when Synaptics is enabled.

MFC r281440:

Improve Synaptics support for newer touchpads.

Enable two finger scrolling by default and disable the edge scrolling if
the touchpad has no physical zone for it. Disable directional scrolling
by default to avoid using extended buttons as scroll buttons.

Add support for ClickPad. On Lenovo laptops, this is the button
reported when one presses the touchpad.

While there, fix a problem where the extended buttons were not reporting
the button release event correctly: we need to save the state of the
buttons and report it to sysmouse until we receive a packet from the
touchpad indicating the button has been released. This makes it
possible to use an extended button to resize a window. On Lenovo
laptops, the major buttons are actually reported as extended buttons.