Allow input config to be under /vendor/odm

Input config should be under /odm when it's "device-specific",
instead of /vendor (for "SoC-specific").

However, not all device have /odm partition so having the fallback
symlink: /odm -> /vendor/odm is important

Bug: 112880217
Test: build
Change-Id: I294e2b172d06d58a42c51c128e448c7644f854dc