wl18xx: print the PHY firmware version from the private static data

The wl18xx firmware writes the PHY firmware version in the static
data.  Add an operation to parse the static data and print the PHY
firmware version when booting.

Signed-off-by: Luciano Coelho <coelho@ti.com>
Signed-off-by: Arik Nemtsov <arik@wizery.com>