staging/speakup: Changed parameters in kstrtol()

Changed parameters in the kstrtol() function inside main.c to resolve
warnings re: mismatched data types used.

Signed-off-by: Lisa Nguyen <lisa@xenapiadmin.com>
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>