tests: System is expecting a kvm_vm param for KvmVM

Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Change-Id: I607b7a7c5a7dec5395267b0fc0a7371032037b16
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/31217
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

tests/gem5/configs/base_config.py

@@ -133,7 +133,7 @@ class BaseSystem(object):
         Arguments:
           system -- System to work on.
         """
-        system.vm = KvmVM()
+        system.kvm_vm = KvmVM()
 
     def init_system(self, system):
         """Initialize a system.