KVM: Fix NX support reporting

NX support is bit 20, not bit 1.
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/x86/kvm/x86.c

@@ -1259,7 +1259,7 @@ static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
 		bit(X86_FEATURE_CMOV) | bit(X86_FEATURE_PSE36) |
 		bit(X86_FEATURE_MMX) | bit(X86_FEATURE_FXSR) |
 		bit(X86_FEATURE_SYSCALL) |
-		(bit(X86_FEATURE_NX) && is_efer_nx()) |
+		(is_efer_nx() ? bit(X86_FEATURE_NX) : 0) |
 #ifdef CONFIG_X86_64
 		bit(X86_FEATURE_LM) |
 #endif