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

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>
(cherry picked from commit 0c8eb04a6241da28deb108181213b791c378123b)
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>