video: tegra: dc: Avoid FRAME_END_INT conflict

video: tegra: dc: Avoid FRAME_END_INT conflict

Allowing for dc->lock to be acquired by the
caller in function tegra_dc_config_frame_end_intr
can result in FRAME_END_INT mask register being
overwritten if the lock is actually acquired by
another thread.

Refactor the critical section into its own function
and allow callers to call either function. Also
Change the name of tegra_dc_wait_for_frame_end
to indicate that it should be called with dc->lock
locked.

Bug 1534724

Change-Id: I87b1fc529f29f707a1bdadf18efa6bb19d6966b3
Signed-off-by: Daniel Solomon <daniels@nvidia.com>
Reviewed-on: http://git-master/r/456988
Reviewed-by: Jon Mayo <jmayo@nvidia.com>
Tested-by: Jon Mayo <jmayo@nvidia.com>