Input: i8042 - select ARCH_MIGHT_HAVE_PC_SERIO on unicore32

Architectures which might use an i8042 for serial IO to keyboard,
mouse, etc should select ARCH_MIGHT_HAVE_PC_SERIO.

Signed-off-by: Mark Salter <msalter@redhat.com>
Acked-by: Guan Xuetao <gxt@mprc.pku.edu.cn>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>