usb: musb: sunxi: Fix accessing an released usb phy

In the Linux kernel, the following vulnerability has been resolved:

usb: musb: sunxi: Fix accessing an released usb phy

Commit 6ed05c68cbca ("usb: musb: sunxi: Explicitly release USB PHY on

exit") will cause that usb phy @glue->xceiv is accessed after released.

1) register platform driver @sunxi_musb_driver

// get the usb phy @glue->xceiv

sunxi_musb_probe() -> devm_usb_get_phy().

2) register and unregister platform driver @musb_driver

musb_probe() -> sunxi_musb_init()

use the phy here

//the phy is released here

musb_remove() -> sunxi_musb_exit() -> devm_usb_put_phy()

3) register @musb_driver again

musb_probe() -> sunxi_musb_init()

use the phy here but the phy has been released at 2).

...

Fixed by reverting the commit, namely, removing devm_usb_put_phy()

from sunxi_musb_exit().