Input: i8042 - cleanup SERIO_I8042 dependencies

Remove messy dependencies from SERIO_I8042 by having it depend on one
Kconfig symbol (ARCH_MIGHT_HAVE_PC_SERIO) and having architectures
which need it select ARCH_MIGHT_HAVE_PC_SERIO in arch/*/Kconfig.
New architectures are unlikely to need SERIO_I8042, so this avoids
having an ever growing list of architectures to exclude.

Signed-off-by: Mark Salter <msalter@redhat.com>
Acked-by: "H. Peter Anvin" <hpa@zytor.com>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>