Staging: rtl8723au: rtl8723a_bt-coexist: Remove unused variable

A variable is initialized and then assigned values in the code but is
never used and therefore, should be removed.
Semantic patch used:
@@
type T;
identifier i;
constant C;
position p != e.p;
@@

- T i@p;
  <+... when != i
- i = C;
  ...+>

Signed-off-by: Shivani Bhardwaj <shivanib134@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>