* Fold module installation into kernel image recipe.
* Specify make argument to strip modules on installation instead of
explicitly invoking the strip tool.
* Remove support of TARGET_KERNEL_MODULES, it's a phony target thus
we're not allowed to depend on it per Android 10 restriction. It
has been useless for years anyway.
* Apply minor clean-ups.
Change-Id: I288af1b2f741f524c2ef49554e15cb91c3115209