v4l2_codec2: Convert Android.mk for libv4l2_codec2_vda and libv4l2_code2_arcva_factory to Android.bp

libv4l2_codec2_vda and libv4l2_code2_arcva_factory are required to be imported by
device/google/cheets/codec2/allocators/Android.bp. The allocators is also required to be imported by
device/google/cheets/codec2/vdastore/Android.bp.
Because shared library built by Android.mk is not visible by Android.bp. There is a need to convert
Android.mk buidling libv4l2_codec2_vda and libv4l2_codec2_arcva_factory to Android.bp.

Bug: 32691050
Test: build Android image
Change-Id: I245ef18bdd1cc7280df718a8df5f7a42580375a2

In addition, build only if hardware/google/av is visible.

Bug: 74403547
Test: builds
Change-Id: I8da9be96013822a006a5de135e508259019d672e

Bug: 72354012
Test: setprop debug.stagefright.ccodec_v4l2 true
Test: stagefright -S -N c2.v4l2.h264.decoder bear.mp4
Change-Id: I24c4595fbbd7b085ab37a99183433e422242b555