KVM: use a more sensible error number when debugfs directory creation fails

I don't know if this was due to cut and paste, or somebody was really
using a D20 to pick the error code for kvm_init_debugfs as suggested by
Linus (EFAULT is 14, so the possibility cannot be entirely ruled out).

In any case, this patch fixes it.

Reported-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index a9dd682..1cf9ccb 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3091,7 +3091,7 @@
 static int kvm_init_debug(void)
-	int r = -EFAULT;
+	int r = -EEXIST;
 	struct kvm_stats_debugfs_item *p;
 	kvm_debugfs_dir = debugfs_create_dir("kvm", NULL);