ARC: [plat-hsdk]: Enable AXI DW DMAC in defconfig

For some reasons my previous patch "Enable AXI DW DMAC support"
was applied only partially (only device tree part).
So enable AXI DW DMAC in HSDK defconfig to be able to use it in
verification flow.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>