Some stats reported by ethtool -S on mv643xx_eth device are cleared
between each call.  This patch fixes it.
Signed-off-by: Maxime Bizon <mbizon@freebox.fr>
Signed-off-by: Dale Farnsworth <dale@farnsworth.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
        for (offset = ETH_MIB_BAD_OCTETS_RECEIVED;
                        offset <= ETH_MIB_FRAMES_1024_TO_MAX_OCTETS;
                        offset += 4)
-               *(u32 *)((char *)p + offset) = read_mib(mp, offset);
+               *(u32 *)((char *)p + offset) += read_mib(mp, offset);
 
        p->good_octets_sent += read_mib(mp, ETH_MIB_GOOD_OCTETS_SENT_LOW);
        p->good_octets_sent +=
        for (offset = ETH_MIB_GOOD_FRAMES_SENT;
                        offset <= ETH_MIB_LATE_COLLISION;
                        offset += 4)
-               *(u32 *)((char *)p + offset) = read_mib(mp, offset);
+               *(u32 *)((char *)p + offset) += read_mib(mp, offset);
 }
 
 /*