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>