net: dsa: b53: Stop exporting b53_phylink_* routines

They are not used outside of the b53_common.c file, no need to be
exported.

Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://lore.kernel.org/r/20240423183339.1368511-2-florian.fainelli@broadcom.com


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