KVM: Fix NX support reporting

NX support is bit 20, not bit 1.

Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7c1ce5a..834a7bf 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1259,7 +1259,7 @@
 		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