drm: Drop crtc argument from __drm_atomic_helper_crtc_destroy_state

It's unused, and really this helper should only look at the state
structure and nothing else.

v2: Rebase on top of rockchip changes

v3: Drop unrelated hunk, spotted by Laurent.

v4: Rebase onto mtk driver merge.

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Eric Anholt <eric@anholt.net>
Cc: Mark Yao <mark.yao@rock-chips.com>
Acked-by: Thierry Reding <thierry.reding@gmail.com>
Acked-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1462804451-15318-1-git-send-email-daniel.vetter@ffwll.ch