PKCS#7: Add a missing static

Add a missing static (found by checker).
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>

crypto/asymmetric_keys/pkcs7_trust.c

@@ -23,7 +23,7 @@
 /**
  * Check the trust on one PKCS#7 SignedInfo block.
  */
-int pkcs7_validate_trust_one(struct pkcs7_message *pkcs7,
+static int pkcs7_validate_trust_one(struct pkcs7_message *pkcs7,
 				    struct pkcs7_signed_info *sinfo,
 				    struct key *trust_keyring)
 {