checkpatch: check for #if 0/#if 1

Warn if #if 1 or #if 0 is present.

Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>
(cherry picked from commit a81f92c9abe442ad5b00e8df31172f145a14af3f)

Conflicts:

	scripts/checkpatch.pl

Change-Id: Id28c07eaa907351933e0450751b05e2f749d23d0