ARM: dts: imx6qdl-gw551x: fix audio SSI

The audio codec on the GW551x routes to ssi1.  It fixes audio capture on
the device.

Cc: stable@vger.kernel.org
Fixes: 3117e851 ("ARM: dts: imx: Add TDA19971 HDMI Receiver to GW551x")
Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>