vmwgfx cleanups and fixes.

* 'drm-vmwgfx-fixes' of ssh://people.freedesktop.org/~syeh/repos_linux:
  drm/vmwgfx: Adjust checks for null pointers in 13 functions
  drm/vmwgfx: Use memdup_user() rather than duplicating its implementation
  drm/vmwgfx: Use kmalloc_array() in vmw_surface_define_ioctl()
  drm/vmwgfx: Avoid validating views on view destruction
  drm/vmwgfx: Limit the user-space command buffer size
  drm/vmwgfx: Remove a leftover debug printout
  drm/vmwgfx: Allow resource relocations on byte boundaries
  drm/vmwgfx: Enable SVGA_3D_CMD_DX_TRANSFER_FROM_BUFFER command
  drm/vmwgfx: Remove call to reservation_object_test_signaled_rcu before wait
  drm/vmwgfx: Replace numeric parameter like 0444 with macro