realtek: pcs: rtl930x: move CMU reset into PLL config

realtek: pcs: rtl930x: move CMU reset into PLL config

Move resetting the CMU into the PLL configuration itself where the speed
is set. Since this operation is not dependent of the target SerDes and
only needs to be called if the speed changed, it fits better there.
Though the call was guarded with a 'speed_changed' before, this also
applies to actually changing the speed. This was done before anyway,
even if the speed value hasn't really changed.

Signed-off-by: Jonas Jelonek <jelonek.jonas@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/22198
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>