Staging: rtl8192u: r819xU_firmware: removed commented out assert

Removed an assert that was commented out. The comment provides
no documentation value as rt_status is properly handled.

Signed-off-by: Tolga Ceylan <tolga.ceylan@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>