fixup: "nova: update to r6 nova kernel branch"

Issue #1211
Revert "timer: apply PIT quirk to avoid high cpu load"

This reverts commit edc03489b308dba055957813d296e56aa947a3a0.

Since commit

"timer: nova specific version of the service"

a nova specific timer is used and this quirk is not necessary anymore.

Issue #1211