Use Make command for all OnePlus Kernels instead of oplus build scripts.

It is noticed that this method builds only the required kernel without modules and vendor boot and decreases the build time especially for Bazel Builds drastically.

- Search Clang path in Source and System.
- Fix Uname when building with Make.
- Remove unwanted script code and add exit on system clang selected
- Build with -O2 compiler options

Co-authored-by: fatalcoder524 <[email protected]>

Author: Bouteillepleine