staging/rtl8712: remove event_tasklet

This is unused.

Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Link: https://lore.kernel.org/r/20220411151620.129178-6-dave@stgolabs.net


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>