tg3: Fix TSO loopback test

Commit bb158d69, entitled
"tg3: Add TSO loopback test", mistakenly inverted the checksum field
test from the receive BD.  This patch corrects the problem.
Signed-off-by: NMatt Carlson <mcarlson@broadcom.com>
Reviewed-by: NMichael Chan <mchan@broadcom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/tg3.c

@@ -11195,7 +11195,7 @@ static int tg3_run_loopback(struct tg3 *tp, u32 pktsz, int loopback_mode)
 			}
 		} else if ((desc->type_flags & RXD_FLAG_TCPUDP_CSUM) &&
 			   (desc->ip_tcp_csum & RXD_TCPCSUM_MASK)
-			    >> RXD_TCPCSUM_SHIFT == 0xffff) {
+			    >> RXD_TCPCSUM_SHIFT != 0xffff) {
 			goto out;
 		}