octeontx2-af: Use u64_to_ether_addr() to convert ethernet address

Use u64_to_ether_addr() to convert a u64 value to an Ethernet MAC address,
instead of directly calculating, as this is exactly what this
function does.
Signed-off-by: Li Zetao <lizetao1@huawei.com>
Acked-by: Geethasowjanya Akula <gakula@marvell.com>
Link: https://lore.kernel.org/r/20230808114504.4036008-3-lizetao1@huawei.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/marvell/octeontx2/af/rvu_cgx.c

@@ -686,7 +686,7 @@ int rvu_mbox_handler_cgx_mac_addr_get(struct rvu *rvu,
 {
 	int pf = rvu_get_pf(req->hdr.pcifunc);
 	u8 cgx_id, lmac_id;
-	int rc = 0, i;
+	int rc = 0;
 	u64 cfg;
 
 	if (!is_cgx_config_permitted(rvu, req->hdr.pcifunc))
@@ -697,8 +697,7 @@ int rvu_mbox_handler_cgx_mac_addr_get(struct rvu *rvu,
 	rsp->hdr.rc = rc;
 	cfg = cgx_lmac_addr_get(cgx_id, lmac_id);
 	/* copy 48 bit mac address to req->mac_addr */
-	for (i = 0; i < ETH_ALEN; i++)
-		rsp->mac_addr[i] = cfg >> (ETH_ALEN - 1 - i) * 8;
+	u64_to_ether_addr(cfg, rsp->mac_addr);
 	return 0;
 }