DMA: PL330: Use devm_* functions

devm_* functions are device managed and make the code and error
handling a bit simpler.

Cc: Jassi Brar <jassisinghbrar@gmail.com>
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>