drm: switch drm_handle_t to unsigned int

This converts the drm_handle_t to unsigned int.
This is currently safe to do as we don't pass these across the kernel/user
boundary, but userspace does use these, but no-one builds userspace against
the kernel headers at present so it is okay to switch over the kernel copy
of drm.h at this point. (The CVS tree will switch over soon in sync with
some Mesa changes)

From: Egbert Eich <eich@suse.de>
Signed-off-by: Dave Airlie <airlied@linux.ie>