tests/avocado: extend the timeout for x86_64 tcg tests

These are timing out on gitlab.

Acked-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20221027183637.2772968-7-alex.bennee@linaro.org>
diff --git a/tests/avocado/boot_linux.py b/tests/avocado/boot_linux.py
index b7522ad..571d338 100644
--- a/tests/avocado/boot_linux.py
+++ b/tests/avocado/boot_linux.py
@@ -19,6 +19,7 @@ class BootLinuxX8664(LinuxTest):
     """
     :avocado: tags=arch:x86_64
     """
+    timeout = 480
 
     def test_pc_i440fx_tcg(self):
         """