drm/core: get rid of -Iinclude/drm

This results in a warning when building out of tree:
"cc1: warning: include/drm: No such file or directory [enabled by default]"

Most code already uses #include <drm/foo.h> correctly, so fix the
instances that don't.
Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/Makefile

@@ -2,8 +2,6 @@
 # Makefile for the drm device driver.  This driver provides support for the
 # Direct Rendering Infrastructure (DRI) in XFree86 4.1.0 and higher.
 
-ccflags-y := -Iinclude/drm
-
 drm-y       :=	drm_auth.o drm_bufs.o drm_cache.o \
 		drm_context.o drm_dma.o \
 		drm_fops.o drm_gem.o drm_ioctl.o drm_irq.o \

drivers/gpu/drm/drm_flip_work.c

@@ -21,8 +21,8 @@
  * SOFTWARE.
  */
 
-#include "drmP.h"
-#include "drm_flip_work.h"
+#include <drm/drmP.h>
+#include <drm/drm_flip_work.h>
 
 /**
  * drm_flip_work_allocate_task - allocate a flip-work task