net: stmmac: create dwmac-intel.c to contain all Intel platform

As stmmac_pci.c file is getting bigger and more complex, it is reasonable
to separate all the Intel specific dwmac pci device to a different file.
This move includes Intel Quark, TGL and EHL. A new kernel config
CONFIG_DWMAC_INTEL is introduced and depends on X86. For this initial
patch, all the necessary function such as probe() and exit() are identical
besides the function name.

Signed-off-by: Voon Weifeng <weifeng.voon@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/Kconfig

@@ -198,6 +198,15 @@ config DWMAC_SUN8I
  EMAC ethernet controller.
 endif
 
+config DWMAC_INTEL
+ tristate "Intel GMAC support"
+ default X86
+ depends on X86 && STMMAC_ETH && PCI
+ depends on COMMON_CLK
+ ---help---
+ This selects the Intel platform specific bus support for the
+ stmmac driver. This driver is used for Intel Quark/EHL/TGL.
+
 config STMMAC_PCI
  tristate "STMMAC PCI bus support"
  depends on STMMAC_ETH && PCI

drivers/net/ethernet/stmicro/stmmac/Makefile

@@ -30,5 +30,6 @@ obj-$(CONFIG_DWMAC_GENERIC) += dwmac-generic.o
 stmmac-platform-objs:= stmmac_platform.o
 dwmac-altr-socfpga-objs := altr_tse_pcs.o dwmac-socfpga.o
 
+obj-$(CONFIG_DWMAC_INTEL) += dwmac-intel.o
 obj-$(CONFIG_STMMAC_PCI) += stmmac-pci.o
 stmmac-pci-objs:= stmmac_pci.o