mei: bus: add client dma interface

Expose the client dma mapping via mei client bus interface.
The client dma has to be mapped before the device is enabled,
therefore we need to create device linking already during mapping
and we need to unmap after the client is disable hence we need to
postpone the unlink and flush till unmapping or when
destroying the device.

Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Co-developed-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20210420172755.12178-1-emmanuel.grumbach@intel.com
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20211112062814.7502-1-emmanuel.grumbach@intel.com