drm/i915: Handle dma fences in dirtyfb callback

Take into account dma fences in dirtyfb callback. If there is no
unsignaled dma fences perform flush immediately. If there are
unsignaled dma fences perform invalidate and add callback which will
queue flush when the fence gets signaled.

v4:
 - Move invalidate before callback is added
v3:
 - Check frontbuffer bits before adding any fence fb
 - Flush only when adding fence cb succeeds
v2: Use dma_resv_get_singleton

Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230901093500.3463046-5-jouni.hogander@intel.com