ntb: off by one sanity checks

commit ad3e2751 upstream.

These tests are off by one.  If "mw" is equal to NTB_NUM_MW then we
would go beyond the end of the ndev->mw[] array.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jon Mason <jon.mason@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>