drm/radeon: Remove unused function pointer typedef radeon_packet3_check_t

Remove the 'radeon_packet3_check_t' typedef as it is not used.
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Chen Lin <chen.lin5@zte.com.cn>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/radeon.h

@@ -1105,9 +1105,6 @@ struct radeon_cs_packet {
 typedef int (*radeon_packet0_check_t)(struct radeon_cs_parser *p,
 				      struct radeon_cs_packet *pkt,
 				      unsigned idx, unsigned reg);
-typedef int (*radeon_packet3_check_t)(struct radeon_cs_parser *p,
-				      struct radeon_cs_packet *pkt);
-
 
 /*
  * AGP