btfm: provide a way to query wcn3990 status

provide a way to query wcn3990 status. Audio hal
uses this to cleanup its stack when BT is turned off
or SCO is disconnected during SCO devices selection.

CRs-Fixed: 2061191
Change-Id: I3c10559c6ca34692c7f147b5cc2f0101b0bfbbf9
Signed-off-by: Satish Kodishala <skodisha@codeaurora.org>