drm: fixup r300 scratch on BE machines

This fixes the r300 scratch stuff to work on PPC,
from Ben Herrenschmidt on IRC.
Signed-off-by: Dave Airlie <airlied@linux.ie>

drivers/char/drm/r300_cmdbuf.c

@@ -723,7 +723,7 @@ static int r300_scratch(drm_radeon_private_t *dev_priv,
 	
 	dev_priv->scratch_ages[header.scratch.reg]++;
 	
-	ref_age_base = *(u32 **)cmdbuf->buf;
+	ref_age_base =  (u32 *)(unsigned long)*((uint64_t *)cmdbuf->buf);
 	
 	cmdbuf->buf += sizeof(u64);
 	cmdbuf->bufsz -= sizeof(u64);