net: dsa: bcm_sf2: communicate integrated PHY revision to PHY driver

The integrated BCM7xxx PHY contains no useful revision information
in its MII_PHYSID2 bits 3:0, that information is instead contained in
the SWITCH_REG_PHY_REVISION register.

Read this register, store its value, and return it by implementing the
dsa_switch::get_phy_flags() callback accordingly. The register layout is
already matching what the BCM7xxx PHY driver is expecting to find.

Signed-off-by: Florian Fainelli <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
diff --git a/drivers/net/dsa/bcm_sf2.h b/drivers/net/dsa/bcm_sf2.h
index 260bab3..d3bd52d 100644
--- a/drivers/net/dsa/bcm_sf2.h
+++ b/drivers/net/dsa/bcm_sf2.h
@@ -26,6 +26,7 @@
 struct bcm_sf2_hw_params {
 	u16	top_rev;
 	u16	core_rev;
+	u16	gphy_rev;
 	u32	num_gphy;
 	u8	num_acb_queue;
 	u8	num_rgmii;