ethernet: constify references to netdev->dev_addr in drivers

This big patch sprinkles const on local variables and
function arguments which may refer to netdev->dev_addr.

Commit 406f42fa0d3c ("net-next: When a bond have a massive amount
of VLANs...") introduced a rbtree for faster Ethernet address look
up. To maintain netdev->dev_addr in this tree we need to make all
the writes to it got through appropriate helpers.

Some of the changes here are not strictly required - const
is sometimes cast off but pointer is not used for writing.
It seems like it's still better to add the const in case
the code changes later or relevant -W flags get enabled
for the build.

No functional changes.

Link: https://lore.kernel.org/r/20211014142432.449314-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c
index 4422bae..617d0e4 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c
@@ -634,7 +634,7 @@ static void sun8i_dwmac_set_mac(void __iomem *ioaddr, bool enable)
  * If addr is NULL, clear the slot
  */
 static void sun8i_dwmac_set_umac_addr(struct mac_device_info *hw,
-				      unsigned char *addr,
+				      const unsigned char *addr,
 				      unsigned int reg_n)
 {
 	void __iomem *ioaddr = hw->pcsr;