ALSA: include: Add new ioctl for metadata mode

Add a new ioctl to support metadata mode in lpa driver. This ioctl
allows lpa driver to work in default alsa compliant mode and also
metadata mode.

CRs-Fixed: 458904
Change-Id: I8111e8652bbfb6dd93bdbda69bd16f53b45cb756
Signed-off-by: Krishnankutty Kolathappilly <kkolat@codeaurora.org>