drm/bridge: add drm_for_each_bridge_in_chain_from()

Add variant of drm_for_each_bridge_in_chain_scoped() that iterates on the
encoder bridge from a given bridge until the end of the chain.

Reviewed-by: Maxime Ripard <[e-mail]>
Link: https://lore.kernel.org/r/20[e-mail]
Signed-off-by: Luca Ceresoli <[e-mail]>

include/drm/drm_bridge.h

···
 	     bridge;							\
 	     bridge = drm_bridge_get_next_bridge_and_put(bridge))
 
+/**
+ * drm_for_each_bridge_in_chain_from - iterate over all bridges starting
+ *                                     from the given bridge
+ * @first_bridge: the bridge to start from
+ * @bridge: a bridge pointer updated to point to the current bridge at each
+ *	    iteration
+ *
+ * Iterate over all bridges in the encoder chain starting from
+ * @first_bridge, included.
+ *
+ * Automatically gets/puts the bridge reference while iterating, and puts
+ * the reference even if returning or breaking in the middle of the loop.
+ */
+#define drm_for_each_bridge_in_chain_from(first_bridge, bridge)		\
+	for (struct drm_bridge *bridge __free(drm_bridge_put) =		\
+		     drm_bridge_get(first_bridge);			\
+	     bridge;							\
+	     bridge = drm_bridge_get_next_bridge_and_put(bridge))
+
 enum drm_mode_status
 drm_bridge_chain_mode_valid(struct drm_bridge *bridge,
 			    const struct drm_display_info *info,