[SCSI] libfc: set both precision and field with when printing FC IDs

Most of the prints of fabric IDs were specified as %6x, which will not
print any leading 0s.  It's nice to see leading 0s for identifiers
like this, which are a fixed length.  This patch sets the precision
modifier as well, making the specifier %6.6x, which forces the
printing of leading 0s.

Signed-off-by: Chris Leech <christopher.leech@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>