dt-bindings: net: qcom,ethqos: add description for sa8775p

Add the compatible for the MAC controller on sa8775p platforms. This MAC
works with a single interrupt so add minItems to the interrupts property.
The fourth clock's name is different here so change it. Enable relevant
PHY properties. Add the relevant compatibles to the binding document for
snps,dwmac as well.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>