gralloc: Set min_sdk_version

Modules contributing mainline modules (APK/APEX) should set
min_sdk_version.

For now setting min_sdk_version doesn't change build outputs.
But build-time checks will be added soon.

Bug: 152655956
Test: m
Change-Id: I06644a725eb8f4ce0c7d8e1f09359b55e1b668d7