ASoC: bg: Register codec only once ADSP is up

Sound card should not get registered till ADSP is up, hence
defer codec registration till the ADSP is up. Add a
flag in packetizer to indicate init complete.

Change-Id: I846049b586698ea6b29a651a9c2c65311a478723
Signed-off-by: Ashish Jain <ashishj@codeaurora.org>