lantiq-xway: remove support for AVM FRITZ!Box 7320 7330 7330SL

This device has broken Ethernet on both ports.

Remove support for those devices. for now, as there was no feedback from
the original author.

Closes #1943

(cherry picked from commit 5231fb01)

docs/user/supported_devices.rst

@@ -265,9 +265,6 @@ lantiq-xway
 * AVM
 
   - FRITZ!Box 7312 [#avmflash]_
-  - FRITZ!Box 7320 [#avmflash]_ [#lan_as_wan]_
-  - FRITZ!Box 7330 [#avmflash]_ [#lan_as_wan]_
-  - FRITZ!Box 7330 SL [#avmflash]_ [#lan_as_wan]_
 
 mpc85xx-generic
 ---------------

targets/lantiq-xway

@@ -2,7 +2,3 @@ device('avm-fritz-box-7312', 'avm_fritz7312', {
 	factory = false,
 })
 
-device('avm-fritz-box-7320', 'avm_fritz7320', {
-        factory = false,
-        aliases = {'avm-fritz-box-7330', 'avm-fritz-box-7330-sl'},
-})