usb: musb: handle irqs in the order dictated by programming guide

MUSB's programming guide dictates how we should handle its
irqs and in which order. Follow that.

Signed-off-by: Arnaud Mandy <ext-arnaud.2.mandy@nokia.com>
Signed-off-by: Felipe Balbi <felipe.balbi@nokia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>