net: pcs: lynx: add lynx_pcs_create_fwnode()

commit  f75294770af50e7c9156606bc2a897082818fd03 from
https://github.com/nxp-imx/linux-imx lf-6.1.y

Add a helper to create a lynx PCS from a fwnode handle.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
(cherry picked from commit 6e1a1282

)
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Xiaolei Wang <xiaolei.wang@windriver.com>