CHROMIUM: camx: fix inconsistent lock state at cam_sync_signal()

Disable BH so that we don't take this lock from soft-irq
context.

UPSTREAM-TASK=b:274966069
BUG=b:361680626
TEST=camera.HAL3Preview on coachz with lockdep enabled
TEST=camera.HAL3StillCapture on coachz with lockdep

Change-Id: I06b4474b900bb43131a92a0fe699c1a260f7a99b
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/5806139


Reviewed-by: Ricardo Ribalda <ribalda@chromium.org>
(cherry picked from commit c70f3457b68a0c58f71c9f1c1efe6e39b981b6fb)
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/5826169


Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Signed-off-by: Hubert Mazur <hmazur@google.com>