drm: remove old backwards compatibilty stuff

/** \name Backward compatibility section */

/*@{*/

#ifndef MODULE_LICENSE

#define MODULE_LICENSE(x)

#endif

#ifndef preempt_disable

#define preempt_disable()

#define preempt_enable()

#endif

#ifndef pte_offset_map

#define pte_offset_map pte_offset

#define pte_unmap(pte)

#endif

#define DRM_RPR_ARG(vma) vma,

#define VM_OFFSET(vma) ((vma)->vm_pgoff << PAGE_SHIFT)