Add support for keyboard input from the VNC server in the PS/2 keyboard model. The introduced code is based on the functionality in the Arm PL050 KMI model. Change-Id: If04a9713e5a15e2149d1a7471b999e3060d8ee7d Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com> Reviewed-on: https://gem5-review.googlesource.com/9763 Reviewed-by: Gabe Black <gabeblack@google.com> Maintainer: Gabe Black <gabeblack@google.com>