wl18xx: print new RDL versions during boot

Extract and print info for the new RDL 5, 6, 7 and 8.
Replace const struct with function which translates
the RDL number to string.

Signed-off-by: Victor Goldenshtein <victorg@ti.com>
Signed-off-by: Barak Bercovitz <barak@wizery.com>
Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>