x25: bit and/or confusion in x25_ioctl()?

Looking at commit ebc3f64b it appears that this was intended
and not the original, equivalent to `if (facilities.reverse & ~0x81)'.

In x25_parse_facilities() that patch changed how facilities->reverse
was set. No other bits were set than 0x80 and/or 0x01.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>