usb: musb: twl: use mailbox API to send VBUS or ID events

The atomic notifier from twl4030/twl6030 to notifiy VBUS and ID events,
is replaced by a direct call to omap musb blue.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>