Input: fixup X86_MRST selects

Some of the recent X86_MRST additions make some "select"s
conditional on X86_MRST but missed some related kconfig symbols,
causing:

drivers/built-in.o: In function `ps2_end_command':
(.text+0x257ab2): undefined reference to `i8042_check_port_owner'
drivers/built-in.o: In function `ps2_end_command':
(.text+0x257ae1): undefined reference to `i8042_unlock_chip'
drivers/built-in.o: In function `ps2_begin_command':
(.text+0x257b40): undefined reference to `i8042_check_port_owner'
drivers/built-in.o: In function `ps2_begin_command':
(.text+0x257b6f): undefined reference to `i8042_lock_chip'

when SERIO_I8042=m, SERIO_LIBPS2=y, KEYBOARD_ATKBD=y.

We need to make i8042 dependant upon !X86_MRST and allow deselecting
atkbd on Moorestown even when !CONFIG_EMBEDDED.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Jacob Pan <jacob.jun.pan@intel.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>