sdm: Define Socket Handler interface

1. Define Socket Handler interface for SDM.
2. Add HWC Socket Handler implementation.
3. SDM will use this interface to get the platform specific DPPS
   Socket fd from HWC.

CRs-Fixed: 1099069
Change-Id: I8c3b48306d4ee994133990a160e4c4f3a90b1875
16 files changed