dmaengine: rcar-dmac: refactor the error handling code of rcar_dmac_probe

dmaengine: rcar-dmac: refactor the error handling code of rcar_dmac_probe

In rcar_dmac_probe, if pm_runtime_resume_and_get fails, it forgets to
disable runtime PM. And of_dma_controller_free should only be invoked
after the success of of_dma_controller_register.

Fix this by refactoring the error handling code.

Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20211020143546.3436205-1-mudongliangabcd@gmail.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>