sound: usb: Add support to share iova with remote processor

ISOC data transfer for audio device is offloaded to remote
usb audio driver entity. This requires remote entity to access
device context info, event ring, transfer rings and transfer
buffers allocated by APPS XHCI device. Hence add a platform
device which maps the XHCI device physical memory to virtual
memory and shares with remote processor's iommu. All the memory
info is then sent over QMI to remote entity.

Change-Id: I1abc80652a167cefa667b914b3a80a87326c3d44
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
Signed-off-by: Jack Pham <jackp@codeaurora.org>