dmaengine: rcar-dmac: clear channel register when error

We need to clear channel register in error case as recovery.
The channel is already stopped in such case, thus we don't need to call
rcar_dmac_chan_halt() before clearing.

rcar_dmac_chan_halt() will clear and confirm DE bit.
But it will be failed because channel is already stopped in error case.
In other words, we shouldn't call it then.

Reported-by: Hiroki Negishi <hiroki.negishi.bx@renesas.com>
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reviewed-by: Hiroki Negishi <hiroki.negishi.bx@renesas.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Vinod Koul <vkoul@kernel.org>