stmmac: intel: Fixes clock registration error seen for multiple interfaces

Issue seen when enumerating multiple Intel mGbE interfaces in EHL.

[    6.898141] intel-eth-pci 0000:00:1d.2: enabling device (0000 -> 0002)
[    6.900971] intel-eth-pci 0000:00:1d.2: Fail to register stmmac-clk
[    6.906434] intel-eth-pci 0000:00:1d.2: User ID: 0x51, Synopsys ID: 0x52

We fix it by making the clock name to be unique following the format
of stmmac-pci_name(pci_dev) so that we can differentiate the clock for
these Intel mGbE interfaces in EHL platform as follow:

  /sys/kernel/debug/clk/stmmac-0000:00:1d.1
  /sys/kernel/debug/clk/stmmac-0000:00:1d.2
  /sys/kernel/debug/clk/stmmac-0000:00:1e.4

Fixes: 58da0cfa ("net: stmmac: create dwmac-intel.c to contain all Intel platform")
Signed-off-by: Wong Vee Khee <vee.khee.wong@intel.com>
Signed-off-by: Voon Weifeng <weifeng.voon@intel.com>
Co-developed-by: Ong Boon Leong <boon.leong.ong@intel.com>
Signed-off-by: Ong Boon Leong <boon.leong.ong@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/dwmac-intel.c

@@ -233,6 +233,7 @@ static void common_default_data(struct plat_stmmacenet_data *plat)
 static int intel_mgbe_common_data(struct pci_dev *pdev,
 				  struct plat_stmmacenet_data *plat)
 {
+	char clk_name[20];
 	int ret;
 	int i;
 
@@ -301,8 +302,10 @@ static int intel_mgbe_common_data(struct pci_dev *pdev,
 	plat->eee_usecs_rate = plat->clk_ptp_rate;
 
 	/* Set system clock */
+	sprintf(clk_name, "%s-%s", "stmmac", pci_name(pdev));
+
 	plat->stmmac_clk = clk_register_fixed_rate(&pdev->dev,
-						   "stmmac-clk", NULL, 0,
+						   clk_name, NULL, 0,
 						   plat->clk_ptp_rate);
 
 	if (IS_ERR(plat->stmmac_clk)) {