staging: speakup: Remove unnecessary test in if condition

Remove unnecessary test on synth->alive since it has already been
tested previously.

This fixes the following smatch warning:
drivers/staging/speakup/synth.c:182 spk_synth_is_alive_restart() warn:
we tested 'synth->alive' before and it was 'false'

Signed-off-by: Amitoj Kaur Chawla <amitoj1606@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>