dmaengine: qcom: gpi: set DMA_PRIVATE capability

dmaengine: qcom: gpi: set DMA_PRIVATE capability

The GPI DMA controller is only responsible for QUP peripherals, and
cannot work as a general-purpose DMA accelerator.

Set DMA_PRIVATE capability for it.

This fixes error messages about GPI being shown when an async-tx
consumer is loaded.

Fixes: 5d0c3533a19f ("dmaengine: qcom: Add GPI dma driver")
Signed-off-by: Icenowy Zheng <zhengxingda@iscas.ac.cn>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Link: https://patch.msgid.link/20260602070344.3707256-1-zhengxingda@iscas.ac.cn
Signed-off-by: Vinod Koul <vkoul@kernel.org>