ASoc: Fix for dtmf tone play issue

Fix the data corruption happening because of
misaligned datatypes so that DTMF can be played
for more than 32767 seconds.

Change-Id: I199d6d10e9f184665d8f03a2265d0bcd8ae16590
Signed-off-by: Jhansi Konathala <cjkonat@codeaurora.org>