net: mdio: realtek-rtl9300: use command runner for read_c45()

net: mdio: realtek-rtl9300: use command runner for read_c45()

Convert the read_c45() path to the new command runner. This needs the
additional helper otto_emdio_read_cmd() that can issue the command runner
and process a read operation. It is basically nothing more than

- run the command
- read the command result thorugh the I/O register

With this in place convert the read_c45() like the alread existing write
C22/C45 implementation.

- bus calls otto_emdio_read_c45()
- this handed over to SoC specific otto_emdio_9300_read_c45()
- the registers are filled
- the otto_emdio_read_cmd() is issued
- that calls the command runner

Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20260527163449.1294961-4-markus.stockhausen@gmx.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>