net: phylink: move manual flow control setting

Move the handling of manual flow control configuration to a common
location during resolve. We currently evaluate this for all but
fixed links.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://patch.msgid.link/E1t9RQe-002Feh-T1@rmk-PC.armlinux.org.uk


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