Revert "drm/omapdrm: cleanup: drm_modeset_lock_all() --> DRM_MODESET_LOCK_ALL_BEGIN()"

Revert "drm/omapdrm: cleanup: drm_modeset_lock_all() --> DRM_MODESET_LOCK_ALL_BEGIN()"

This reverts commit a59385096ecbf04f343d379e61349296d93edbbd.

This patchset breaks on intel platforms and was previously NACK'd by
Ville.

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Fernando Ramos <greenfoo@u92.eu>
Acked-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20211002154542.15800-8-sean@poorly.run