Input: cypress_ps2 - fix waiting for command response

Input: cypress_ps2 - fix waiting for command response

Commit 8bccf667f62a ("Input: cypress_ps2 - report timeouts when reading
command status") uncovered an existing problem with cypress_ps2 driver:
it tries waiting on a PS/2 device waitqueue without using the rest of
libps2. Unfortunately without it nobody signals wakeup for the
waiting process, and each "extended" command was timing out. But the
rest of the code simply did not notice it.

Fix this by switching from homegrown way of sending request to get
command response and reading it to standard ps2_command() which does
the right thing.

Reported-by: Woody Suwalski <terraluna977@gmail.com>
Tested-by: Woody Suwalski <terraluna977@gmail.com>
Fixes: 8bccf667f62a ("Input: cypress_ps2 - report timeouts when reading command status")
Link: https://lore.kernel.org/r/a8252e0f-dab4-ef5e-2aa1-407a6f4c7204@gmail.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>