Known issue: PV list limitation: support to max 32 drives

[Leo-Yan]

So far, it's predefined to support max 32 drives for PV list, this is mainly caused by the message transferring is not flexible so we use the fixed string array to pass PV list.

The limitation is relevant with the macros:
https://github.com/Seagate/propeller/blob/master/src/ilm.h#L9
https://github.com/Seagate/lvm2-stx-private/blob/centos7_lvm2/lib/locking/lvmlockd.c#L24
https://github.com/Seagate/lvm2-stx-private/blob/centos7_lvm2/daemons/lvmlockd/lvmlockd-internal.h#L24