iwlwifi: support reading and storing EWRD revisions 1 and 2

As an extension to the WRDS support for revisions 1 and 2, do the same
for the EWRD tables.  These tables have a very similar format to the
WRDS table, so most of the code is similar.

Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20210805141826.2d5494de683c.Ia024b1368873d488906a639e29454cbbdc788d03@changeid


Signed-off-by: Luca Coelho <luciano.coelho@intel.com>