dev: Drop include of drm/drm.h in kfd_ioctl.h.

I don't have this header on one of the machines I build on, so this is
breaking the build for me. Removing this include seems to make the
build succeed, implying that it's not actually necessary. I looked at
the file it's used in and didn't see anything that looked like it came
from this header file.

Change-Id: If4a29063d6d0d25904183cab78c9713ff1f8daa6
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/48603
Reviewed-by: Matthew Poremba <matthew.poremba@amd.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/dev/hsa/kfd_ioctl.h

@@ -24,7 +24,6 @@
 #define KFD_IOCTL_H_INCLUDED
 
 #include <cstdint>
-#include <drm/drm.h>
 #include <linux/ioctl.h>
 #include <linux/types.h>