Check all keys despite early failure

In the kasp script, if one expected key is not found, continue checking
the other key ids, even if there is no match for the first one.  This
provides a bit more information which keys mismatch and makes for
easier debugging test failures.

bin/tests/system/kasp.sh

@@ -728,6 +728,7 @@ check_numkeys() {
 
 _check_keys() {
 	ret=0
+	_ret=0
 
 	# Clear key ids.
 	key_set KEY1 ID "no"
@@ -770,10 +771,10 @@ _check_keys() {
 
 		# If ret is still non-zero, none of the files matched.
 		echo_i "failed"
-		return 1
+		_ret=1
 	done
 
-	return 0
+	return $_ret
 }
 
 # Check keys for a configured zone. This verifies: