REORG/MINOR: ssl: using enum for SSL mode async

Author: prometherion

build/haproxy_spec.yaml

@@ -269,7 +269,10 @@ definitions:
           type: string
           x-display-name: SSL Default Server Options
         ssl_mode_async:
-          type: boolean
+          enum:
+          - enabled
+          - disabled
+          type: string
           x-display-name: Asynchronous TLS I/O operations
         stats_timeout:
           type: integer

models/configuration.yaml

@@ -59,7 +59,8 @@ global:
       type: string
       x-display-name: SSL Default Server Ciphersuites
     ssl_mode_async:
-      type: boolean
+      type: string
+      enum: [enabled, disabled]
       x-display-name: Asynchronous TLS I/O operations
     cpu_maps:
       x-go-name: CPUMaps