realtek: pcs: rtl930x: enhance symbol error reset

realtek: pcs: rtl930x: enhance symbol error reset

The symbol error reset function misses the default sequence. E.g. kernel
spits the message "rtpcs_930x_sds_sym_err_reset unsupported phy mode" when
working on 2500base-x.

Align the function with the SDK by

- adding QSGMII mode
- adding the "all other modes" switch
- working with "channels" to make clearer what happens

Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Link: https://github.com/openwrt/openwrt/pull/21718
Signed-off-by: Robert Marko <robimarko@gmail.com>