UPSTREAM: ASoC: Intel: sst: Remove unused STREAM_DECODE and STREAM_RESET states

STREAM_DECODE is completely unused, status == STREAM_RESET was checked
for, but never set, remove both.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
(cherry picked from commit de983347)
Signed-off-by: Samaga Prasanna Krishna <samaga.krishna@intel.corp-partner.google.com>

BUG=b:110025789
TEST=Test Audio use cases with full SOF 0.6 rebase release series applied.

Change-Id: Ifbad1a1e96ef8da98dc8754f6c1037a42fbbcd15
Reviewed-on: https://chromium-review.googlesource.com/1353424


Commit-Ready: Curtis Malainey <cujomalainey@chromium.org>
Tested-by: Curtis Malainey <cujomalainey@chromium.org>
Reviewed-by: Curtis Malainey <cujomalainey@chromium.org>