drm/amd/display: Refine globallock.

Switch to wait_for_completion_interruptible_timeout wait
since the lock is called from IOCTL context and can be
interrupted by a signal.

Global lock function might return EDEADLK or EINTR which
is not an error and just singals to user mode to restart
the call.

Signed-off-by: Andrey Grodzovsky <Andrey.Grodzovsky@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>