KEYS: Remove key_type::match in favour of overriding default by match_preparse

A previous patch added a ->match_preparse() method to the key type.  This is
allowed to override the function called by the iteration algorithm.
Therefore, we can just set a default that simply checks for an exact match of
the key description with the original criterion data and allow match_preparse
to override it as needed.

The key_type::match op is then redundant and can be removed, as can the
user_match() function.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>

include/linux/key-type.h

@@ -113,10 +113,6 @@ struct key_type {
 	 */
 	int (*match_preparse)(struct key_match_data *match_data);
 
-	/* match a key against a description */
-	int (*match)(const struct key *key,
-		     const struct key_match_data *match_data);
-
 	/* Free preparsed match data (optional).  This should be supplied it
 	 * ->match_preparse() is supplied. */
 	void (*match_free)(struct key_match_data *match_data);