drm/amd: drop use of drmP.h from all header files

Drop use of the deprecated drmP.h header file from
all amd header files.
This makes it a more smooth process to get rid of drmP.h
in the .c files.

Added include files and forwards as appropriate.

Signed-off-by: Sam Ravnborg <[e-mail]>
Reviewed-by: Alex Deucher <[e-mail]>
Cc: "Christian König" <[e-mail]>
Cc: "David (ChunMing) Zhou" <[e-mail]>
Cc: David Airlie <[e-mail]>
Cc: Daniel Vetter <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/amd/amdgpu/amdgpu_sched.h

···
 #ifndef __AMDGPU_SCHED_H__
 #define __AMDGPU_SCHED_H__
 
-#include <drm/drmP.h>
+enum drm_sched_priority;
+
+struct drm_device;
+struct drm_file;
 
 enum drm_sched_priority amdgpu_to_sched_priority(int amdgpu_priority);
 int amdgpu_sched_ioctl(struct drm_device *dev, void *data,

drivers/gpu/drm/amd/amdgpu/amdgpu_trace.h

···
 #include <linux/types.h>
 #include <linux/tracepoint.h>
 
-#include <drm/drmP.h>
-
 #undef TRACE_SYSTEM
 #define TRACE_SYSTEM amdgpu
 #define TRACE_INCLUDE_FILE amdgpu_trace

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h

···
 #ifndef __AMDGPU_DM_H__
 #define __AMDGPU_DM_H__
 
-#include <drm/drmP.h>
 #include <drm/drm_atomic.h>
+#include <drm/drm_connector.h>
+#include <drm/drm_crtc.h>
+#include <drm/drm_dp_mst_helper.h>
+#include <drm/drm_plane.h>
 
 /*
  * This file contains the definition for amdgpu_display_manager