The 'snps,ptp-ref-clk-rate' and 'snps,ptp-req-clk-rate' properties
are not supported by the stmmac driver currently, so remove
them from the sa8155p-adp ethernet node as well.

Cc: Bjorn Andersson <andersson@kernel.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Vinod Koul <vkoul@kernel.org>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Bhupesh Sharma <bhupesh.sharma@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20220907204153.2039776-1-bhupesh.sharma@linaro.org