powerpc/83xx: fix use-after-free on mpc831x_usb_cfg()

[Markus Elfring]

> The np variable is still being used after the of_node_put() call,

> which may result in use-after-free.

> We fix this issue by calling of_node_put() after the last usage.


I imagine that this commit description can be improved a bit more
(by mentioning the influence of “immr_node”?).
How do you think about to omit the word “We” here?


> This patatch also do some cleanup.


Should the renaming of a jump label be contributed in a separate update
step of a small patch series besides a wording without a typo?

Regards,
Markus