Fix LV status parsing to accept newer LVM

LVM version 2.02.93 (or at least, sometimes after .88) has extend the
lv_attr field with two more flag; we only care about the first digit,
so let's change the "!= 6" check to "< 6".

Thanks to Robin H Johnson <robbat2@gentoo.org> for finding this issue.

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: René Nussbaumer <rn@google.com>