staging: lustre: o2iblnd: use bool assignment to true/false

Replace 0 with false in tx_pages_mapped = 0 to be consistent with
the rest of the lustre code.

Signed-off-by: Nicholas Hanley <nicholasjhanley@gmail.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>