tests/vm: make --interactive (and therefore DEBUG=1) unconditional

While the concept of only dropping to ssh if a test fails is nice it
is more useful for this to be unconditional. You usually just want to
get the build up and running and then noodle around debugging or
attempting to replicate.

Cc: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>

tests/vm/basevm.py

@@ -403,7 +403,7 @@ def main(vmcls):
     exitcode = 0
     if vm.ssh(*cmd) != 0:
         exitcode = 3
-    if exitcode != 0 and args.interactive:
+    if args.interactive:
         vm.ssh()
 
     if not args.snapshot: