drm/amdgpu: drop drmP.h from vcn_v2_5.c

Unused.
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/vcn_v2_5.c

@@ -22,7 +22,7 @@
  */
 
 #include <linux/firmware.h>
-#include <drm/drmP.h>
+
 #include "amdgpu.h"
 #include "amdgpu_vcn.h"
 #include "soc15.h"