KVM: x86: Free wbinvd_dirty_mask if vCPU creation fails

commit 16be9dde upstream.

Free the vCPU's wbinvd_dirty_mask if vCPU creation fails after
kvm_arch_vcpu_init(), e.g. when installing the vCPU's file descriptor.
Do the freeing by calling kvm_arch_vcpu_free() instead of open coding
the freeing.  This adds a likely superfluous, but ultimately harmless,
call to kvmclock_reset(), which only clears vcpu->arch.pv_time_enabled.
Using kvm_arch_vcpu_free() allows for additional cleanup in the future.

Fixes: f5f48ee1 ("KVM: VMX: Execute WBINVD to keep data consistency with assigned devices")
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[bwh: Backported to 3.16: Also delete the preceding fx_free(), since
 kvm_arch_vcpu_free() calls it.]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>