realtek: pcs: rtl838x: drop redundant reset writes

realtek: pcs: rtl838x: drop redundant reset writes

Sometimes redundancy is so obvious that one likely misses it. Trying to
bring all SerDes setup into a unified shape, one thinks twice if
something is really needed or not.

For the RTL838x case, the single writes for take/release reset were still
an outlier. Looking closer at them one can see that the same bits are all
covered already in deactivate/activate. So before, they have been put
into the desired state but those outlier writes mess with them again.

[0, 3, 0x7146/0x7106] just deals with the SOFT_RST bit that is already
covered by rtpcs_838x_sds_reset.

[0, 0, 0xc00] touches multiple bits, amongst the EN_RX/EN_TX bits
already covered in deactivate/active. Moreover, it potentially forces
other bits into a state causing broken functionality, e.g.
INV_HSI/INV_HSO which deal with the polarity. This has no effect right
no right now but might be a latent issue in the future.

Also move the reset call down to the end of the function, doing a
soft/RX reset after every configuration is done. This is likely what the
SDK also intended, and mirrors the 839x behavior.

Link: https://github.com/openwrt/openwrt/pull/23746
Signed-off-by: Jonas Jelonek <jelonek.jonas@gmail.com>