audio: optimize DDR fifo management

audio: optimize DDR fifo management

PD#150616: optimize audio DDR FIFO management driver.

Previously, we need to set DDR num and DDR IRQ number
in each audio devices.

This commit add one DDR manager which manipulate all
the ddr num and irq stuffs.
Make other audio driver easy to use it by simple interface.

Change-Id: Ie9688e651a4eff6fd4135811c50aa343e89580fe
Signed-off-by: Shuai Li <shuai.li@amlogic.com>