config: allow Array line to contain array name without /dev/md/ prefix.

config: allow Array line to contain array name without /dev/md/ prefix.

For consistency with --create and --assemble, allow the array name
given in mdadm.conf to exclude the "/dev/md/" prefix.  So e.g.

  ARRAY home uuid=whatever

is treated like

  ARRAY /dev/md/home uuid=whatever

Also exclude names which create_mddev will reject.

Signed-off-by: NeilBrown <neilb@suse.de>