hal: Enable parsing of interface tag independent of backend_tag

- Current platform_info file parsing assumes backend tag to be present
always with hw_interface tag.
-With multiCopp changes as we have to have hw_interface entry for
all supported device, it should not be mandatory to have backend_tag.
-Decouple hw_interface from backend_tag.

Change-Id: I1c1163273d92305deac787ccecdcceb1f6943532