net: phylink: use neg_mode in phylink_mii_c22_pcs_decode_state()

Rather than using the state of the Autoneg bit, which is unreliable
with the new PCS neg mode support, use the passed neg_mode to decide
whether to decode the link partner advertisement data.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Tested-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Link: https://patch.msgid.link/E1tXGed-000EtF-CN@rmk-PC.armlinux.org.uk


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