drm: replace weird conditional includes

pte_wrprotect() is only used by drm_vm.c, so move the include there. Also
include it unconditionally, all architectures provide this header!

Furthermore, replace asm/current.h with sched.h, which includes
asm/current.h unconditionally. This way we get the same effect and avoid
direct asm/ includes. Furthermore, drop the weird __alpha__ protection.
It's safe to include sched.h everywhere (and the wait.h comment doesn't
apply, anyway).

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/drm_vm.c

@@ -40,6 +40,7 @@
 #include <linux/efi.h>
 #include <linux/slab.h>
 #endif
+#include <asm/pgtable.h>
 #include "drm_legacy.h"
 
 struct drm_vma_entry {

include/drm/drmP.h

@@ -36,12 +36,7 @@
 #define _DRM_P_H_
 
 #ifdef __KERNEL__
-#ifdef __alpha__
-/* add include of current.h so that "current" is defined
- * before static inline funcs in wait.h. Doing this so we
- * can build the DRM (part of PI DRI). 4/21/2000 S + B */
-#include <asm/current.h>
-#endif				/* __alpha__ */
+#include <linux/sched.h>
 #include <linux/kernel.h>
 #include <linux/kref.h>
 #include <linux/miscdevice.h>
@@ -58,9 +53,6 @@
 #include <linux/io.h>
 #include <linux/slab.h>
 #include <linux/ratelimit.h>
-#if defined(__alpha__) || defined(__powerpc__)
-#include <asm/pgtable.h>	/* For pte_wrprotect */
-#endif
 #include <asm/mman.h>
 #include <asm/uaccess.h>
 #include <linux/types.h>