libstagefright: Add pause support for hardware omx component

-ADSP doesn't enter sleep state after wma playback is paused
and power suspended.
-No support for NT session pause in case of hardware component.
NT session need to be paused to put ADSP into power collapse.
-Add support of pause in stagefright to ensure device enters
suspend mode. Also add intermediate states to avoid concurrency
issues between read and pause.

Change-Id: I87b0992f3d4d580c3a68d27fbed6b65d2200dda9
CRs-Fixed: 496256