mdadm: fix update=resync regression

mdadm: fix update=resync regression

mdadm --assemble --update=resync started failing  with the error
"mdadm: --update=resync not understood for 1.x metadata".

It is a regression. Add omitted branch to fix error.

Resubmitted, original author is not responding.
https://lore.kernel.org/linux-raid/ZZqJlCToUS3Qrl4J@bianca.dpss.psy.unipd.it/

Fixes: 7e8daba8b793 ("super1: refactor the code for enum")
Signed-off-by: Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>