x86: crownbay: Enable on-board SMSC superio keyboard controller

x86: crownbay: Enable on-board SMSC superio keyboard controller

So far we only enabled one legacy serial port on the SMSC LPC47m
superio chipset on Intel Crown Bay board. As the board also has
dual PS/2 ports routed out, enable the keyboard controller which
is i8042 compatible so that we can use PS/2 keyboard and mouse.

In order to make PS/2 keyboard work with the VGA console, remove
CONFIG_VGA_AS_SINGLE_DEVICE. To boot Linux kernel with PIC mode
using PIRQ routing table, adjust the mask in the device tree to
reserve irq12 which is used by PS/2 mouse.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>