Staging: speakup: Remove unused variable

This patch removes variable that was used to store only the return value of a function call.

The issue was detected and resolved using the following coccinelle script:

@@
expression ret;
identifier f;
@@

 -ret =
 +return
    f(...);
 -return ret;

Signed-off-by: Haneen Mohammed <hamohammed.sa@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>