ASoC: Intel: haswell: fix initialize 'NULL device *' issue

Add initialization for sst_hsw.dev at init stage, which fix the
'NULL device *' warning issues.

Signed-off-by: Jie Yang <yang.jie@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/sound/soc/intel/haswell/sst-haswell-ipc.c b/sound/soc/intel/haswell/sst-haswell-ipc.c
index f95f271..f6efa9d 100644
--- a/sound/soc/intel/haswell/sst-haswell-ipc.c
+++ b/sound/soc/intel/haswell/sst-haswell-ipc.c
@@ -2119,6 +2119,8 @@
 	if (hsw == NULL)
 		return -ENOMEM;
 
+	hsw->dev = dev;
+
 	ipc = &hsw->ipc;
 	ipc->dev = dev;
 	ipc->ops.tx_msg = hsw_tx_msg;