Thanks to Paulo Zanoni for indirectly pointing this out.

Looks like we never actually added any code for checking whether or not
we actually wrote watermark levels properly. Let's fix that.

Changes since v1:
- Use %u instead of %d when printing WM state mismatches
Signed-off-by: Lyude <cpaul@redhat.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1476480722-13015-10-git-send-email-cpaul@redhat.com