realtek: pcs: introduce dedicated SerDes ops
Add a dedicated structure for SerDes operations. This will be used for
several common operations currently called individually in various
places of the code.
Start with defining the basic read and write operations for a SerDes in
this structure. Use generic implementations of these operations for all
variants (RTL83xx, RTL93xx) for now.
Signed-off-by: Jonas Jelonek <jelonek.jonas@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/21592
Signed-off-by: Robert Marko <robimarko@gmail.com>