usb: musb: dsps: remove explicit NOP device creation

As NOP device node is now added in am33xx tree so remove the call
which creates the NOP platform_device.

Signed-off-by: Ajay Kumar Gupta <ajay.gupta@ti.com>
Signed-off-by: Santhapuri, Damodar <damodar.santhapuri@ti.com>
Signed-off-by: Ravi Babu <ravibabu@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>