net: mdio: realtek-rtl9300: use command runner for write_c22()

net: mdio: realtek-rtl9300: use command runner for write_c22()

Now that the driver has a generic command runner make use of it in the
write_c22() path. For this.

- add generic otto_emdio_write_c22() helper that will be called by bus
- convert otto_emdio_9300_write_c22() to new command runner logic

Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20260527163449.1294961-3-markus.stockhausen@gmx.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>