DMA: PL330: Fix build warning

This patch adds to fix the build warning as following.

drivers/dma/pl330.c: In function 'pl330_probe':
drivers/dma/pl330.c:859: warning: comparison of distinct pointer types lacks a cast

Signed-off-by: Boojin Kim <boojin.kim@samsung.com>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>