staging: rtl8192u: dm_shadow_init() is not used

The function dm_shadow_init() is not used anywhere, remove it.

Signed-off-by: Michael Straube <straube.linux@gmail.com>
Link: https://lore.kernel.org/r/20230312073247.9822-3-straube.linux@gmail.com


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