staging:rtl8192u: Removed unused CMPK_RX_DBG_MSG_SIZE - Style

Remove the unused macro definition CMPK_RX_DBG_MSG_SIZE. This is a
coding style change which should have no impact on runtime code
execution.

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