net: phylink: add common validation for sfp_select_interface()

Whenever we call sfp_select_interface(), we check the returned value
and print an error. There are two cases where this happens with the
same message. Provide a common function to do this.

Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Tested-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://patch.msgid.link/E1t3bcQ-000c85-S4@rmk-PC.armlinux.org.uk


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