Revert "Input: fixup X86_MRST selects"

This reverts commit 0b28bac5.

After adding x86_platform's detection for i8042 controller, we
don't need the force dependency on !X86_MRST any more

Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Feng Tang <feng.tang@intel.com>
LKML-Reference: <1278342202-10973-5-git-send-email-feng.tang@intel.com>
Acked-by: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>