staging: bcm2835-audio: double free in init error path

commit 136ff5e49271c4c8fceeca5491c48e66b961564b upstream.

We free instance here and in the caller.  It should be only the caller
which handles it.

Fixes: d7ca3a71 ("staging: bcm2835-audio: Operate non-atomic PCM ops")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>