net: stmmac: dwmac-qcom-ethqos: shrink clock code with devres

We can use a devm action to completely drop the remove callback and use
stmmac_pltfr_remove() directly for remove. We can also drop one of the
goto labels.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Andrew Halaney <ahalaney@redhat.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>