Add existing multipath devices to wwids file on

Add existing multipath devices to wwids file on

When multipathd started up, it didn't add any existing devices to the
wwids file.  Because of this, devices that were always set up in the
initramfs were not counted as valid multipath devices, and checking
if one of their paths was a multipath path device gave the incorrect
answer.  This patch makes multipath add those devices when it does
its initial configuration on startup.

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>