KVM: VMX: Always signal #GP on WRMSR to MSR_IA32_CR_PAT with bad value

The behavior of WRMSR is in no way dependent on whether or not KVM
consumes the value.

Fixes: 4566654b ("KVM: vmx: Inject #GP on invalid PAT CR")
Cc: stable@vger.kernel.org
Cc: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>