ARM: dts: sun7i: Add external phy clock node
fixup! ARM: dts: sun7i: Add correct DMA settings for sunxi GMAC

Remove bogus parameter
fixup! ARM: sunxi: Extend stmmac to support GMAC in Allwinner A20 SoC's

Add proper clock support
fixup! ARM: dts: sun7i: Add GMAC controller node to sun7i DTSI

Use external phy clock reference for "stmmaceth" clock,
and ahb gmac clock gate for "ahb_gmac" clock.