ARM: dts: qcom: ipq8064: add missing snps,dwmac compatible for gmac

Add missing snps,dwmac compatible for gmac ipq8064 dtsi.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Tested-by: Jonathan McDowell <noodles@earth.li>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@somainline.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220707010943.20857-5-ansuelsmth@gmail.com