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>

net/ceph/crypto.c

@@ -476,7 +476,6 @@ struct key_type key_type_ceph = {
 	.preparse	= ceph_key_preparse,
 	.free_preparse	= ceph_key_free_preparse,
 	.instantiate	= generic_key_instantiate,
-	.match		= user_match,
 	.destroy	= ceph_key_destroy,
 };