drm/radeon/kms: fix up for BIG ENDIAN breakage

Commit 308e5bcb ("drm: add an fb creation ioctl that takes a pixel
format v5") missed one spot needing to be fixed up in the __BIG_ENDIAN
case.

Fixes build error:

drivers/gpu/drm/radeon/radeon_fb.c: In function
'radeonfb_create_pinned_object':
drivers/gpu/drm/radeon/radeon_fb.c:144:18: error: 'struct drm_mode_fb_cmd2'
has no member named 'bpp'
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/radeon_fb.c

@@ -141,7 +141,7 @@ static int radeonfb_create_pinned_object(struct radeon_fbdev *rfbdev,
 		tiling_flags = RADEON_TILING_MACRO;
 
 #ifdef __BIG_ENDIAN
-	switch (mode_cmd->bpp) {
+	switch (bpp) {
 	case 32:
 		tiling_flags |= RADEON_TILING_SWAP_32BIT;
 		break;