staging:rtl8192u: Removed unused structure BSS_QOS - Style

The structure BSS_QOS is not used in code so has simply been removed. The
change is a coding style change and should not impact runtime execution.

Signed-off-by: John Whitmore <johnfwhitmore@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>