[maguro] Fixes for bluetooth, rild, audio and ducati firmware loading

1) Let the bcm firmware service not stall the boot process
2) Create a symlink to /dev/mmcblk0p9 as rild crashes if the modem is not at it's hardcoded location
3) Remove invalid pulseaudio sink for bluetooth
4) Load RPMSG kernel modules in early boot for the ducati firmware to load
I wonder if this could instead be done by some udev rules?