Add a dedicated helper 'rtpcs_931x_sds_power' to power down/up a SerDes.
Up to now, plain register writes to the corresponding register were used
in several places and with slightly different syntax. Use the helper to
replace the existing boilerplate code for powering on/off SerDes.
Signed-off-by: Jonas Jelonek <jelonek.jonas@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/21184
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
b43f7bc9c2