Staging: rtl8723au: Add blank line after declarations

WARNING: "Missing a blank line after declarations"
Add blank line after declarations. That was found by running checkpatch

Signed-off-by: Melike Yurtoglu <aysemelikeyurtoglu@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>