dma: Add lockdep asserts to virt-dma

Add lockdep asserts to all functions with "vc.lock must be held by
caller" in their documentation. This will help catch cases where these
assumptions do not hold.

Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://lore.kernel.org/r/20240308210034.3634938-4-sean.anderson@linux.dev
Signed-off-by: Vinod Koul <vkoul@kernel.org>