drm/msm/sde: add ability to force panic before recovery

Define a new bit in the debugfs dbg_ctrl node to allow the
driver to trigger a kernel panic instead of executing
hardware recovery on commit errors. This is useful during
test and debugging phases of driver development.

Change-Id: I7af0589e2b19c2336a978b89c8097a3e0c2561f6
Signed-off-by: Clarence Ip <cip@codeaurora.org>