usb: phy: ab8500-usb: update irq handling code

Update irq handling code to notify all possible link status changes of
AB8500 and AB8505 to the ux500-musb glue driver.  The additional event
codes will be used for pm-runtime implementation, and are defined in a
separate ux500-specific header.

This also modify the irq registration code to use devm_* helpers and
drop all non necessary fail path code.

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Fabio Baltieri <fabio.baltieri@linaro.org>
Signed-off-by: Felipe Balbi <balbi@ti.com>