checkpatch: Add warnings for use of mdelay()

Discourage the use of mdelay(), and use msleep() instead.

Change-Id: I99f44fc632df4b371bc8633005d57c220ece1001
Signed-off-by: Israel Schlesinger <israels@codeaurora.org>
(cherry picked from commit 084af58596758be6e51ef060aefa2cd622dc9205)
Signed-off-by: Stepan Moskovchenko <stepanm@codeaurora.org>
Signed-off-by: Raghavendra Rao Ananta <rananta@codeaurora.org>