staging: r8188eu: remove unnecessary initialization

The variable 'retsig' in odm_signal_scale_mapping() is set in the
function before it returns, so it is not needed to initialize it.

Tested-by: Philipp Hortmann <philipp.g.hortmann@gmail.com> # Edimax N150
Signed-off-by: Michael Straube <straube.linux@gmail.com>
Link: https://lore.kernel.org/r/20220911161949.11293-4-straube.linux@gmail.com


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