ramips: mtk_eth_soc: allow multiple resets

ramips: mtk_eth_soc: allow multiple resets

Use devm_reset_control_array_get_exclusive to register multiple
reset lines in FE driver. This is required to reattach ESW reset to FE
driver again, based on device tree bindings.

While at that, remove unused fe_priv.rst_ppe field, and add error
message if getting the reset fails.

Fixes: 60fadae62b64 ("ramips: ethernet: ralink: move reset of the esw into the esw instead of fe")
Co-developed-by: Maxim Anisimov <maxim.anisimov.ua@gmail.com>
Signed-off-by: Maxim Anisimov <maxim.anisimov.ua@gmail.com>
[Split out of the bigger commit, provide commit mesage, refactor error
handling]
Signed-off-by: Lech Perczak <lech.perczak@gmail.com>