OMAP: omap-mcbsp: Holding min latency constraint

Holding min latency constraint to reduce mp3 playback current.
Deeper states MPU RET/OFF is overhead and consume more power than savings.

Change-Id: Ia69e4ed8a52961e3e2007efbd03d67251066ff4e
Signed-off-by: Raviraj N. Somnache <x0172606@ti.com>
Update topology