staging:rtl8192u: Remove unused Zebra4 bit mask definitions - Style

Remove the unused 'Zebra4' bit mask definitions. These definitions fail
the checkpatch CamelCase naming tests. Rather then renaming, as the
definitions are unused they have simply been removed.

This is a coding style change which should not impact runtime code
execution.

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