Current shdma is using "last" which indicates last desc which needs to have
callback function. But that desc's chunks is always 1, we can use it as finder
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
[reflown changelog for readablity]
Signed-off-by: Vinod Koul <vinod.koul@intel.com>