sdm: Handle non fatal error and fix crash due to uninitialized pointer

1. Fix SF crash observed during DP connection by initializing the
   pointers while parsing the S3D mode.
2. Handle absence of s3d_mode node as non fatal error on DP connect.

Change-Id: Ie596c123727d9d087a0757b4d6c363cec532c2b0
CRs-Fixed: 1061994
1 file changed