tests/functional: Require 'user' netdev for ppc64 e500 test

When commit 72cdd67 extended the ppc64 e500 test to add network
support, it forgot to require the 'user' netdev backend. Fix that.

Fixes: 72cdd67 ("tests/functional: Replace the ppc64 e500 advent calendar test")
Signed-off-by: Cédric Le Goater <[email protected]>
Reviewed-by: Thomas Huth <[email protected]>
Acked-by: Bernhard Beschow <[email protected]>
Reviewed-by: Philippe Mathieu-Daudé <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Thomas Huth <[email protected]>

Author: legoater

tests/functional/test_ppc64_e500.py

@@ -20,6 +20,7 @@ class E500Test(LinuxKernelTest):
 
     def test_ppc64_e500_buildroot(self):
         self.set_machine('ppce500')
+        self.require_netdev('user')
         self.cpu = 'e5500'
 
         uimage_path = self.ASSET_BR2_E5500_UIMAGE.fetch()