update variable names

roles/matrix-awx/surveys/access_export.json.j2

@@ -11,7 +11,7 @@
       "default": "{{ awx_sftp_auth_method | string }}",
       "choices": "Disabled\nPassword\nSSH Key",
       "new_question": true,
-      "variable": "sftp_auth_method",
+      "variable": "awx_sftp_auth_method",
       "type": "multiplechoice"
     },
     {
@@ -23,7 +23,7 @@
       "default": "{{ awx_sftp_password }}",
       "choices": "",
       "new_question": true,
-      "variable": "sftp_password",
+      "variable": "awx_sftp_password",
       "type": "password"
     },
     {
@@ -35,7 +35,7 @@
       "default": "{{ awx_sftp_public_key }}",
       "choices": "",
       "new_question": true,
-      "variable": "sftp_public_key",
+      "variable": "awx_sftp_public_key",
       "type": "text"
     }
   ]