dma: pl330: Implement the dma channel pause/resume interfaces

dma: pl330: Implement the dma channel pause/resume interfaces

This patch implements dma pause and resume interfaces for the
pl330 dmac driver. When the dmaengine_pause callback is called
from audio platform driver, the pl330 driver should handle the
pause command. And when the dmaengine_resume callback function
is called, the pl330 driver should handle the resume command.

In order not to return error code for pause/resume operation,
currently there is nothing implemented for pause and resume
switch interfaces, and there might have some continuous work
for pl330 channel configuration in the future. However, the
odroidx2/u3 board can pause/resume with this implementation.

Change-Id: I584106a4d7861fde308997e6843088fbf0a9b1bb
Signed-off-by: Huang Chao <chao7.huang@samsung.com>