staging: android: logger: Improve logging

Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
staging: logger: Allow to completely disable

* Logger is completely disabled on kernel_common branch.
* Let's disable it via userspace and give option to
  user to re-enable it when required.

Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>

Conflicts:
	drivers/staging/android/logger.c