drm/radeon: drop drmP.h from header files

To ease conversion of .c files drop include of
drmP.h from all header files.
And fix-up build errors caused by this.

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/radeon/atom.c

···
 #include <linux/module.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
+
 #include <asm/unaligned.h>
 
+#include <drm/drm_device.h>
 #include <drm/drm_util.h>
 
 #define ATOM_DEBUG

drivers/gpu/drm/radeon/atom.h

···
 #define ATOM_H
 
 #include <linux/types.h>
-#include <drm/drmP.h>
 
 #define ATOM_BIOS_MAGIC		0xAA55
 #define ATOM_ATI_MAGIC_PTR	0x30

drivers/gpu/drm/radeon/radeon_trace.h

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