struct osmo_sub_auth_data: remove OSMO_DEPRECATED_OUTSIDE

I was the one who suggested adding this attribute during code review,
and now, having realized it was a bad idea, I am removing it.  The
problem is that this attribute spams compilation logs of projects
including file <osmocom/crypt/auth.h>, even if the deprecated struct
is not used directly at all.

Change-Id: Ia5d365206207872d5d3fdd4ae40273eab909fb33
Fixes: 08450c9e "libosmogsm: Support authentication with 256-bit K and/or OP/OPc"
diff --git a/include/osmocom/crypt/auth.h b/include/osmocom/crypt/auth.h
index f73a48b..1499ef8 100644
--- a/include/osmocom/crypt/auth.h
+++ b/include/osmocom/crypt/auth.h
@@ -83,7 +83,7 @@
 			uint8_t ki[OSMO_A5_MAX_KEY_LEN_BYTES];	/*!< secret key */
 		} gsm;
 	} u;
-} OSMO_DEPRECATED_OUTSIDE("Use osmo_sub_auth_data2 instead");
+};
 
 /* data structure describing a computed auth vector, generated by AuC */
 struct osmo_auth_vector {