Make kernel modules into normal installed files

We sometimes see build failures when building platform.zip happens
at the same time as building vendor.img if the vendor.img rule
runs rm -rf $OUT/vendor/lib/modules at the same time that platform.zip
is zipping $OUT/vendor/.  Move the kernel modules into normal
installation rules so that they are in place by the time either
the vendor.img or platform.zip rules run.

This will also cause the kernel modules to show up in
installed-files*.txt.

Test: m vendorimage && ls $OUT/vendor/lib/modules
Change-Id: I178b1d54bfcdb5cf5c29885ace9183ac28fc8826