distro: webos: set PREFERRED_PROVIDER_jpeg to libjpeg-turbo

Use libjpeg-turbo, as it provides SIMD acceleration and improves
performance on applications needing to render many and/or big
JPEG images.

Open-webOS-DCO-1.0-Signed-off-by: Jose Dapena Paz <jose.dapena@palm.com>

Change-Id: I90d7e598d3025a1ac1093ad5a6de8866dce9e6c3
Reviewed-on: https://g2g.palm.com/1923
Reviewed-by: Susan Montooth <susan.montooth@lge.com>
Tested-by: Susan Montooth <susan.montooth@lge.com>