osmo_auth*: fix ordering of function args

milenage_gen_vec() has parameter ordering of (..., auts, rand_auts, rand).

osmo_auth_gen_vec_auts() has (..., rand_auts, auts, rand), but actually feeds
args in the same order, so that its rand_auts becomes auts, and its auts
becomes rand_auts.

Interestingly enough, API user osmo-gen-vec.c also adheres to this misordering
and in turn passes auts for osmo_auth_gen_vec_auts()'s rand_auts and vice
versa, so that it matches milenage_gen_vec().

So both the implementation (milenage_*) and the API user use the same ordering,
just osmo_auth_gen_vec_auts() and osmo_auth_impl{ .gen_vec_auts() } in-between
have the argument names swapped.

Any current user of this API would need to adhere to this swapping or will not
get successful AUTS resolution to a SQN. So the least impact fix is to rename
the args without any actual functional change.

So swap the names rand_auts and auts for osmo_auth_gen_vec_auts() and
osmo_auth_impl{ .gen_vec_auts() }. (Also adjust API doc ordering)

Change-Id: I0dcbd49759fc32d3b8974102dbd1d6703364ebf4
diff --git a/include/osmocom/crypt/auth.h b/include/osmocom/crypt/auth.h
index 37b8a8a..7c6072b 100644
--- a/include/osmocom/crypt/auth.h
+++ b/include/osmocom/crypt/auth.h
@@ -74,7 +74,7 @@
 	/* \brief callback for generationg auth vectors + re-sync */
 	int (*gen_vec_auts)(struct osmo_auth_vector *vec,
 			    struct osmo_sub_auth_data *aud,
-			    const uint8_t *rand_auts, const uint8_t *auts,
+			    const uint8_t *auts, const uint8_t *rand_auts,
 			    const uint8_t *_rand);
 };
 
@@ -83,7 +83,7 @@
 
 int osmo_auth_gen_vec_auts(struct osmo_auth_vector *vec,
 			   struct osmo_sub_auth_data *aud,
-			   const uint8_t *rand_auts, const uint8_t *auts,
+			   const uint8_t *auts, const uint8_t *rand_auts,
 			   const uint8_t *_rand);
 
 int osmo_auth_register(struct osmo_auth_impl *impl);