staging: nvec: ps2: add suspend/resume functions

This adds suspend and resume functions to the nvec_ps2 mouse driver.

During suspend the nvec sends a "Cancel all mouse events" command. If
this is missed, there will be still some bytes in the received buffer
after resume which make the mouse go out of sync.

Signed-off-by: Marc Dietrich <marvin24@gmx.de>
Signed-off-by: Julian Andres Klode <jak@jak-linux.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>