drm: Add compatibility #ifdefs for *BSD

This let's use use the linux drm headers as the canonical source for
libdrm on all platforms.

Signed-off-by: Kristian Høgsberg <krh@bitplanet.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 770772c..db56a6a 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -289,6 +289,9 @@
 typedef int drm_ioctl_compat_t(struct file *filp, unsigned int cmd,
 			       unsigned long arg);
 
+#define DRM_IOCTL_NR(n)                _IOC_NR(n)
+#define DRM_MAJOR       226
+
 #define DRM_AUTH	0x1
 #define	DRM_MASTER	0x2
 #define DRM_ROOT_ONLY	0x4