staging: rtl8723bs: remove unused BT static variables

remove some unused static variables. One of them
is used to toggle on the BT coexistence mechanism,
but it is always enabled and it's not conditioned
to the value of the related parameter.

Remove unused field of the registry_priv struct as
well, they were intended for hosting the parameters
this patch rids.

Signed-off-by: Fabio Aiuto <fabioaiuto83@gmail.com>
Link: https://lore.kernel.org/r/20210729125417.4380-1-fabioaiuto83@gmail.com


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