CI: remove flash_kernel_on_update dependency check (MR 5045)

This property is now handled by boot-deploy, which devices shouldn't
depend on directly anyway.

.ci/testcases/test_device.py

@@ -61,14 +61,6 @@ def test_aports_device(args):
         if "!archcheck" not in apkbuild["options"]:
             raise RuntimeError("!archcheck missing in options= line: " + path)
 
-        if deviceinfo["flash_kernel_on_update"] == "true" \
-                and "postmarketos-update-kernel" not in apkbuild["depends"]:
-            raise RuntimeError(
-                "Deviceinfo indicates this device supports automatic kernel"
-                " flashing on update, but doesn't depend on"
-                " 'postmarketos-update-kernel'. Please add the missing"
-                " dependency.")
-
 
 def test_aports_device_kernel(args):
     """