[media] atmel-isi: tag dma_addr_t as such

[media] atmel-isi: tag dma_addr_t as such

Instead of using u32 for DMA address, use the proper
Kernel type for it.

   drivers/media/platform/soc_camera/atmel-isi.c: In function 'atmel_isi_probe':
>> drivers/media/platform/soc_camera/atmel-isi.c:981:26: warning: passing argument 3 of 'dma_alloc_attrs' from incompatible pointer type
     isi->p_fb_descriptors = dma_alloc_coherent(&pdev->dev,
                             ^

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>