usb : musb : Enabling USB MSC support for DM6446 (TI DaVinci) platform

Enabling USB MSC support for DM6446 (TI DaVinci) platform in the
configuration file.

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>