Fix memory ownership issue in the init function

[diondokter]

So I've been debugging this problem for many days now. Over at my nrf-modem I made this same patch.
It turns out that the params given to the init function need to live forever. Seems like the params aren't copied over, but are still referenced later.

No idea why nobody caught this earlier.
But this fixes it.

If anybody reviews and merges I can publish the new release.

Note though that I have some difficulties to compile this crate now. I think the bindgen version for nrfxlib-sys is quite old now.

[jonathanpallant]

I think the init() function might be unsound - it needs a boolean guard to stop you calling it twice. Otherwise it will re-initialise a heap that might be in use, and over-write a configuration structure that the nrfxlib library might already be using.

[diondokter]

I think the init() function might be unsound - it needs a boolean guard to stop you calling it twice. Otherwise it will re-initialise a heap that might be in use, and over-write a configuration structure that the nrfxlib library might already be using.

I guess you're right. Though calling it twice right now will error anyways. But it becomes unsound just before the error. This is an issue in my version as well.

But look, I'm not that interested in maintaining this crate. I'd rather put the effort in my own. I made this PR mostly for anyone using this because the bug was so nasty.