meta-agl-bsp: meta-ti: pulseaudio: set sink/source for dra7xx-evm

meta-agl-bsp: meta-ti: pulseaudio: set sink/source for dra7xx-evm

pulseaudio, by default, chooses
alsa_output.platform-omap-hdmi-audio.0.auto.analog-stereo as the
default sink. This is not desired since the HDMI is not normally
used as the dra7xx-evm includes an LCD. Configure the CPU board's
alsa_output.platform-sound0.analog-stereo (Line-Out/Headphone)
as the default sink and configure the default source too.

Bug-AGL: SPEC-804

Change-Id: I5d19aa564c8c162d1f5c68ae298d1d25592c8dc9
Signed-off-by: Matt Porter <mporter@konsulko.com>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/10505
Tested-by: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>
ci-image-build: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>
ci-image-boot-test: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>
Reviewed-by: Thomas Rini <trini@konsulko.com>
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>