dmaengine: dw: dmamux: fix OF node leak on route allocation failure

dmaengine: dw: dmamux: fix OF node leak on route allocation failure

commit ec25e60f9f95464aa11411db31d0906b3fb7b9f2 upstream.

Make sure to drop the reference taken to the DMA master OF node also on
late route allocation failures.

Fixes: 134d9c52fca2 ("dmaengine: dw: dmamux: Introduce RZN1 DMA router support")
Cc: stable@vger.kernel.org	# 5.19
Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://patch.msgid.link/20251117161258.10679-6-johan@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>