bgmac: reset cached MAC state during chip reset

Without this bgmac_adjust_link didn't know it should re-initialize MAC
state. This led to the MAC not working after if down & up routine.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/broadcom/bgmac.c b/drivers/net/ethernet/broadcom/bgmac.c
index fd6a22e..273b9f9 100644
--- a/drivers/net/ethernet/broadcom/bgmac.c
+++ b/drivers/net/ethernet/broadcom/bgmac.c
@@ -953,6 +953,8 @@
 			     BGMAC_CMDCFG_CFE |
 			     BGMAC_CMDCFG_SR,
 			     false);
+	bgmac->mac_speed = SPEED_UNKNOWN;
+	bgmac->mac_duplex = DUPLEX_UNKNOWN;
 
 	bgmac_clear_mib(bgmac);
 	if (core->id.id == BCMA_CORE_4706_MAC_GBIT)