staging: wilc1000: rename u16reason in disconnect_info

This patch renames u16reason to reason to remove u16 prefix. There is no
need to use prefix to show data type.

Signed-off-by: Chaehyun Lim <chaehyun.lim@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>