alsa-plugins: Add PACKAGECONFIG for samplerate

:Release Notes:
libsamplerate0 is autodetected from sysroot and still included in some
images (e.g. from incremental and world builds).

:Detailed Notes:

:Testing Performed:
Only build tested.

:QA Notes:
No change to image.

:Issues Addressed:
[ANG-4934] Remove libsamplerate from the image

Open-webOS-DCO-1.0-Signed-off-by: Martin Jansa <martin.jansa@lge.com>

Change-Id: I207394c2a8d9cebac1d7f11dbd584d11c5023385
Reviewed-on: https://g2g.palm.com/5971
Reviewed-by: DCO Verification
Build: Martin Jansa <Martin.Jansa@lge.com>
Reviewed-by: Martin Jansa <Martin.Jansa@lge.com>
Tested-by: Martin Jansa <Martin.Jansa@lge.com>
Reviewed-by: Build Verification
Reviewed-by: Susan Montooth <susan.montooth@lge.com>