Fix compiler warnings for ARM systems.

Signed-off-by: Wolfgang Denk <wd@denx.de>
diff --git a/drivers/s3c4510b_eth.c b/drivers/s3c4510b_eth.c
index 48901aa..3d9066a 100644
--- a/drivers/s3c4510b_eth.c
+++ b/drivers/s3c4510b_eth.c
@@ -175,7 +175,7 @@
 	}
 
 	/* copy user data into frame data pointer */
-	memcpy((void *)(eth->m_curTX_FD->m_frameDataPtr.bf.dataPtr),
+	memcpy((void *)((u32)(eth->m_curTX_FD->m_frameDataPtr.bf.dataPtr)),
 	       (void *)packet,
 	       length);