If MOD_LOAD fails, then MOD_UNLOAD will be called to unwind module
state, but wg_module_init() will have already deinitialized everything
it needs to in a manner that renders it unsafe to call MOD_UNLOAD
after (e.g., freed zone not reset to NULL, wg_osd_jail_slot not reset
to 0). Let's simply stop trying to handle freeing everything in
wg_module_init() to simplify it; let the subsequent MOD_UNLOAD deal with
it, and let's make that robust against partially-constructed state.

While we're here, fix MOD_LOAD to fail if cookie_init() fails;
previously we would hop to the free_crypto label and never set ret to
a proper errno from the 0 it maintained from the previous crypto_init().

PR: 272089