softmac: fix wext MLME request reason code endianness

The MLME request reason code is host-endian and our passing
it to the low level functions is host-endian as well since
they do the swapping. I noticed that the reason code 768 was
sent (0x300) rather than 3 when wpa_supplicant terminates.
This removes the superfluous cpu_to_le16() call.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>