drm/amd/display: Handle I2C-over-AUX write channel status update

[Why]
When writing long AUX commands some sinks will respond will write status
update requiring source to read status.

[How]
When a write request is replied with data (AUX_ACK_M), retry a read of
write status to determine when the write is completed.

Reviewed-by: Martin Leung <Martin.Leung@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Acked-by: Agustin Gutierrez <agustin.gutierrez@amd.com>
Signed-off-by: Aric Cyr <aric.cyr@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/include/i2caux_interface.h

@@ -41,6 +41,8 @@ struct aux_payload {
 	 * reset it to read data */
 	bool write;
 	bool mot;
+	bool write_status_update;
+
 	uint32_t address;
 	uint32_t length;
 	uint8_t *data;
@@ -53,6 +55,7 @@ struct aux_payload {
 	 * zero means "use default value"
 	 */
 	uint32_t defer_delay;
+
 };
 
 struct aux_command {