HBSD: Fix 'find' for the revoked directory

Remove the "No such file or directory" warning generate by find.
Signed-off-by: Loic <loic.f@hardenedbsd.org>
(cherry picked from commit d8866044)

usr.sbin/hbsd-update/hbsd-update

@@ -433,7 +433,7 @@ check_pubkey_validity() {
 
 	updatehash=$(${SHA256} -q ${tmpdir}/pubkey.pem)
 
-	for f in $(${FIND} ${mountpoint}/usr/share/keys/hbsd-update/revoked -type f); do
+	for f in $(${FIND} ${mountpoint}/usr/share/keys/hbsd-update/revoked -type f -print 2>/dev/null); do
 		filehash=$(${SHA256} -q ${f})
 		if [ "${filehash}" = "${updatehash}" ]; then
 			echo "[-] This update has been signed with a revoked key." >&2