dmaengine: sh: rz-dmac: Add DMA clock handling

Currently, DMA clocks are turned on by the bootloader.
This patch adds support for DMA clock handling so that
the driver manages the DMA clocks.

Fixes: 5000d370 ("dmaengine: sh: Add DMAC driver for RZ/G2L SoC")
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20210923102451.11403-1-biju.das.jz@bp.renesas.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>