Staging: rt2860: includecheck fix: rt_linux.h

fix the following 'make includecheck' warning:

  drivers/staging/rt2860/rt_linux.h: linux/wireless.h is included more than once.

Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>