usb : musb : Enabling DM6446 (TI DaVinci) USB module power

Enabling DM6446 (TI DaVinci) USB module power and MUSB low-level
controller hook up to USB core layer.

Signed-off-by: Ravi Babu <ravibabu@ti.com>
Signed-off-by: Swaminathan S <swami.iyer@ti.com>
Signed-off-by: Thomas Abraham <t-abraham@ti.com>
Signed-off-by: Ajay Kumar Gupta <ajay.gupta@ti.com>
Signed-off-by: Remy Bohmer <linux@bohmer.net>