staging: wlan-ng: remove volatile from reapable field in hfa384x_usbctlx

Fix checkpatch.pl warning:

"Use of volatile is usually wrong: see
Documentation/process/volatile-considered-harmful.rs"

reapable is not used to access h/w directly, so volatile is not
necessary.

>From reading the code, the contexts in which the field may be
updated/accessed across threads are protected by the hw->ctlxq.lock
spinlock, where hw is the device struct, so appears thread-safe.

Signed-off-by: Tim Collier <osdevtc@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>