drm.h: Fix DRM compilation with bare-metal toolchain.

An ifdef in drm.h expects to be compiled with full-fledged Linux
toolchain, but it's common to compile kernel with just bare-metal
toolchain which doesn't define __linux__. So, also add __KERNEL__
check.

[nm@ti.com: port forward to 3.9-rc6 and post to dri devel for feedback as RFC]
Signed-off-by: NPaul Sokolovsky <paul.sokolovsky@linaro.org>
Signed-off-by: NDave Airlie <airlied@redhat.com>

include/uapi/drm/drm.h

@@ -36,7 +36,7 @@
 #ifndef _DRM_H_
 #define _DRM_H_
 
-#if defined(__linux__)
+#if defined(__KERNEL__) || defined(__linux__)
 
 #include <linux/types.h>
 #include <asm/ioctl.h>