Input: allow deselecting serio drivers even without CONFIG_EXPERT

There is plenty of consumer hardware (e.g., mac books) that does not use AT
keyboards or PS/2 mice. It therefore makes sense for distro kernels to
build the related drivers as modules to avoid loading them on hardware that
does not need them. As such, these options should no longer be protected by
EXPERT.

Moreover, building these drivers as modules gets rid of the following ugly
error during boot:

[    2.337745] i8042: PNP: No PS/2 controller found. Probing ports directly.
[    3.439537] i8042: No controller found

Signed-off-by: Tom Gundersen <teg@jklm.no>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>