KVM: x86: remove always-false condition in kvmclock_sync_fn

KVM: x86: remove always-false condition in kvmclock_sync_fn

The 'kvmclock_periodic_sync' is a readonly param that cannot change after
bootup.

The kvm_arch_vcpu_postcreate() is not going to schedule the
kvmclock_sync_work if kvmclock_periodic_sync == false.

As a result, the "if (!kvmclock_periodic_sync)" can never be true if the
kvmclock_sync_work = kvmclock_sync_fn() is scheduled.

Link: https://lore.kernel.org/kvm/a461bf3f-c17e-9c3f-56aa-726225e8391d@oracle.com
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Link: https://lore.kernel.org/r/20231001213637.76686-1-dongli.zhang@oracle.com
Signed-off-by: Sean Christopherson <seanjc@google.com>