bgmac: add read of interrupt mask after disabling interrupts

The specs prescribe an immediate read of the interrupt mask after
disabling interrupts.  This patch updates the driver to match the
specs.
Signed-off-by: NNathan Hintz <nlhintz@hotmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bgmac.c

@@ -974,6 +974,7 @@ static void bgmac_chip_intrs_on(struct bgmac *bgmac)
 static void bgmac_chip_intrs_off(struct bgmac *bgmac)
 {
 	bgmac_write(bgmac, BGMAC_INT_MASK, 0);
+	bgmac_read(bgmac, BGMAC_INT_MASK);
 }
 
 /* http://bcm-v4.sipsolutions.net/mac-gbit/gmac/gmac_enable */