net: ethernet: cortina: Implement .set_pauseparam()

The Cortina Gemini ethernet can very well set up TX or RX
pausing, so add this functionality to the driver in a
.set_pauseparam() callback. Essentially just call down to
phylib and let phylib deal with this, .adjust_link()
will respect the setting from phylib.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20240529-gemini-phylib-fixes-v4-3-16487ca4c2fe@linaro.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>