drm/amd/display: release spinlock before committing updates to stream

Currently, amdgpu_do_flip() spinlocks crtc->dev->event_lock and
releases it only after committing updates to the stream.

dc_commit_updates_for_stream() should be moved out of
spinlock for the below reasons:

1. event_lock is supposed to protect access to acrct->pflip_status _only_
2. dc_commit_updates_for_stream() has potential sleep's
   and also its not appropriate to be  in an atomic state
   for such long sequences of code.

Signed-off-by: Shirish S <shirish.s@amd.com>
Suggested-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org