usb: musb: remove duplicated quirks flag

Both musb_io and musb_platform_ops in struct musb define a quirks flag
for the same purpose.  Let's remove the one in struct musb_io, and use
that in struct musb_platform_ops instead.

Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>