KVM: VMX: Move the comment of CR4.MCE handling right above the code

Move the comment about keeping the hosts CR4.MCE loaded in hardware above
the code that actually modifies the hardware CR4 value.

No functional change indented.
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Link: https://lore.kernel.org/r/20230410125017.1305238-3-xiaoyao.li@intel.com
[sean: elaborate in changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>

arch/x86/kvm/vmx/vmx.c

@@ -3389,13 +3389,13 @@ void vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
 {
 	unsigned long old_cr4 = kvm_read_cr4(vcpu);
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
+	unsigned long hw_cr4;
+
 	/*
 	 * Pass through host's Machine Check Enable value to hw_cr4, which
 	 * is in force while we are in guest mode.  Do not let guests control
 	 * this bit, even if host CR4.MCE == 0.
 	 */
-	unsigned long hw_cr4;
-
 	hw_cr4 = (cr4_read_shadow() & X86_CR4_MCE) | (cr4 & ~X86_CR4_MCE);
 	if (is_unrestricted_guest(vcpu))
 		hw_cr4 |= KVM_VM_CR4_ALWAYS_ON_UNRESTRICTED_GUEST;