rb5: Fix HDMI audio playback

Recently updated audio.primary HAL pick up and set the board
specific HDMI mixer control based on the vendor.hw property.

This patch copies and start the service responsible for setting
that vendor.hw property for RB5.

Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
Change-Id: I811d7e80f97c616ea342002a2c33029367e7a559
1 file changed