s3:smbXsrv_open: initialize smbXsrv_open_global->lock_sequence_array with 0xFF

s3:smbXsrv_open: initialize smbXsrv_open_global->lock_sequence_array with 0xFF

This does not match the current documentation, but is very likely the
right thing to do.

If we would match the documentation and initialize with 0x00,
we would return STATUS_SUCCESS without doing any locks.
If the client also follows the documentation and starts
with a lock_sequence of 0 for the first operation.

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Michael Adam <obnox@samba.org>