freezer: comment out might_sleep()

Currently on ARM signal handling here must happen with
interrupts disabled so this might_sleep will cause a
continuous stream of warnings. It is a known issue
upstream.

Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
(cherry picked from commit dc0eed4422dad92d3dd5afd468876d3d5b241ce1)