While cyw43 is deinitialized, an interrupt occurs. That is handled with
these lines: ports/rp2/mpnetworkport.c#L59-L61 and as pendsv is disabled
while in network code, the poll function then just waits there.
When deinit has finished, the poll func is executed, but skipped:
src/cyw43_ctrl.c#L222-L225 this skips the `CYW43_POST_POLL_HOOK` which
would re-enable interrupts, but also reset `cyw43_has_pending`.
And in that state, the lightsleep code, will skip sleeping as it thinks
there is a network packet pending to be handled.
With this change applied, lightsleep works as expected when the wifi chip
is enabled, and when it's powered off.
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