dmaengine: bcm2835: Document struct bcm2835_dmadev

Document the BCM2835 DMA driver's device data structure so that upcoming
commits may add further members with proper kerneldoc.

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: Martin Sperl <kernel@martin.sperl.org>
Cc: Florian Kauer <florian.kauer@koalo.de>

drivers/dma/bcm2835-dma.c

@@ -48,6 +48,12 @@
 #define BCM2835_DMA_CHAN_NAME_SIZE 8
 #define BCM2835_DMA_BULK_MASK  BIT(0)
 
+/**
+ * struct bcm2835_dmadev - BCM2835 DMA controller
+ * @ddev: DMA device
+ * @base: base address of register map
+ * @dma_parms: DMA parameters (to convey 1 GByte max segment size to clients)
+ */
 struct bcm2835_dmadev {
 	struct dma_device ddev;
 	void __iomem *base;