staging: r8188eu: remove PowerIndex_backup from struct dm_priv

The field PowerIndex_backup of struct dm_priv is not used, remove it.

Signed-off-by: Michael Straube <straube.linux@gmail.com>
Link: https://lore.kernel.org/r/20210921194658.10654-6-straube.linux@gmail.com


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