dmaengine: fsl-qdma: Add missing fsl_qdma_format kerneldoc

Document '__reserved2' and 'cmd' fields of 'struct fsl_qdma_format' to
fix W=1 warnings:

  fsl-qdma.c:169 struct member '__reserved2' not described in 'fsl_qdma_format'
  fsl-qdma.c:169 struct member 'cmd' not described in 'fsl_qdma_format'

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20250525-dma-fixes-v1-4-89d06dac9bcb@linaro.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>

Author: krzk

drivers/dma/fsl-qdma.c

@@ -148,6 +148,9 @@
  * @__reserved1:	    Reserved field.
  * @cfg8b_w1:		    Compound descriptor command queue origin produced
  *			    by qDMA and dynamic debug field.
+ * @__reserved2:	    Reserved field.
+ * @cmd:		    Command for QDMA (see FSL_QDMA_CMD_RWTTYPE and
+ *			     others).
  * @data:		    Pointer to the memory 40-bit address, describes DMA
  *			    source information and DMA destination information.
  */