A negative buffer size doesn't make sense and it breaks this check in
ar5523_get_max_rxsz():

	if (!ar->rxbufsz || ar->rxbufsz > AR5523_SANE_RXBUFSZ) { ...
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>