android: skip building drivers as modules

Few Android drivers e.g. uid_cputime and keyreset/combo,
cpufreq_interactive etc.. 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.

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