drm/radeon: Fix sparc regression in r300_scratch()

Commit b4fe945405e477cded91772b4fec854705443dd5 ("drm/radeon: Fix
memory allocation failures in the preKMS command stream checking.")
added a regression in that it completely tossed the get_unaligned()
done by r300_scratch() which we added in commit
958a6f8ccb1964adc3eec84cf401c5baeb4fbca0 ("drm: radeon: Fix unaligned
access in r300_scratch().").

Put it back.

Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Matt Turner <mattst88@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/r300_cmdbuf.c

@@ -921,7 +921,7 @@ static int r300_scratch(drm_radeon_private_t *dev_priv,
 
 	ptr_addr = drm_buffer_read_object(cmdbuf->buffer,
 			sizeof(stack_ptr_addr), &stack_ptr_addr);
-	ref_age_base = (u32 *)(unsigned long)*ptr_addr;
+	ref_age_base = (u32 *)(unsigned long)get_unaligned(ptr_addr);
 
 	for (i=0; i < header.scratch.n_bufs; i++) {
 		buf_idx = drm_buffer_pointer_to_dword(cmdbuf->buffer, 0);