ANDROID: skip building drivers as modules

Few Android drivers e.g. uid_cputime, keyreset/combo
fail to build as kernel modules. Instead of fixing the
build lets make these drivers non-modular (switch config
to "bool" from "tristate" in Kconfig) since Android doesn't
support building kernel modules anyway.

Change-Id: I50c66228c38c8b7c221ec7d6773fcb59bd201be9
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>