DMA: PL330: Remove redundant runtime_suspend/resume functions

The driver's  runtime_suspend/resume functions just disable/enable
the clock which is already being managed at AMBA bus level
runtime_suspend/resume functions.

Hence, remove the driver's runtime_suspend/resume functions.

Signed-off-by: Inderpal Singh <inderpal.singh@linaro.org>
Tested-by: Chander Kashyap <chander.kashyap@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>