mei: hbm: introduce dma bit in the message header

Add dma_ring bit in the mei message header for conveying
that the message data itself are on the dma ring.

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>