dmaengine: dmaengine_desc_callback_valid(): Check for `callback_result`

Before the `callback_result` callback was introduced drivers coded their
invocation to the callback in a similar way to:

	if (cb->callback) {
		spin_unlock(&dma->lock);
		cb->callback(cb->callback_param);
		spin_lock(&dma->lock);
	}

With the introduction of `callback_result` two helpers where introduced to
transparently handle both types of callbacks. And drivers where updated to
look like this:

	if (dmaengine_desc_callback_valid(cb)) {
		spin_unlock(&dma->lock);
		dmaengine_desc_callback_invoke(cb, ...);
		spin_lock(&dma->lock);
	}

dmaengine_desc_callback_invoke() correctly handles both `callback_result`
and `callback`. But we forgot to update the dmaengine_desc_callback_valid()
function to check for `callback_result`. As a result DMA descriptors that
use the `callback_result` rather than `callback` don't have their callback
invoked by drivers that follow the pattern above.

Fix this by checking for both `callback` and `callback_result` in
dmaengine_desc_callback_valid().

Fixes: f067025b ("dmaengine: add support to provide error result from a DMA transation")
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/20211023134101.28042-1-lars@metafoo.deSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/dmaengine.h

@@ -176,7 +176,7 @@ dmaengine_desc_get_callback_invoke(struct dma_async_tx_descriptor *tx,
 static inline bool
 dmaengine_desc_callback_valid(struct dmaengine_desc_callback *cb)
 {
-	return (cb->callback) ? true : false;
+	return cb->callback || cb->callback_result;
 }
 
 struct dma_chan *dma_get_slave_channel(struct dma_chan *chan);