agl-audio-plugin: Fix Pulseaudio version

agl-audio-plugin: Fix Pulseaudio version

Bump Pulseaudio version variable to 9.0 so that the plugin will be
installed in the correct location.

Change-Id: I9328a219b838ed951690a861a10034a87092f89d
Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/9413
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: Matt Ranostay <matt.ranostay@konsulko.com>
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>
Reviewed-by: Stéphane Desneux <stephane.desneux@iot.bzh>
Reviewed-by: Matt Porter <mporter@konsulko.com>
Reviewed-by: Changhyeok Bae <changhyeok.bae@lge.com>