virSCSIHostFindByPCI: Fix link detection

virSCSIHostFindByPCI: Fix link detection

Inside of virSCSIHostFindByPCI() there's a loop which iterates of
entries of "/sys/class/scsi_host" directory trying to identify
all symlinks (which then point to a SCSI device, but that's not
important right now). But the way virFileIsLink() is called can
never return a truthful reply - because it's called over
dent->d_name instead of full path. Fix this by moving the
virFileIsLink() call and passing constructed path into it.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>