drm/amdgpu: drop drmP.h in amdgpu_amdkfd_arcturus.c

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

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

@@ -28,7 +28,6 @@
 #include <linux/uaccess.h>
 #include <linux/mmu_context.h>
 #include <linux/firmware.h>
-#include <drm/drmP.h>
 #include "amdgpu.h"
 #include "amdgpu_amdkfd.h"
 #include "sdma0/sdma0_4_2_2_offset.h"