mon: Fix comparsion typo

Signed-off-by: Jan Friesse <jfriesse@redhat.com>
Reviewed-by: Christine Caulfield <ccaulfie@redhat.com>

exec/mon.c

@@ -315,7 +315,7 @@ static int32_t percent_mem_used_get(void)
 	swap_stats = sg_get_swap_stats();
 #endif
 
-	if (mem_stats == NULL || swap_stats != NULL) {
+	if (mem_stats == NULL || swap_stats == NULL) {
 		log_printf (LOGSYS_LEVEL_ERROR, "Unable to get memory stats: %s",
 			sg_str_error(sg_get_error()));
 		return -1;