KVM: Unconditionally export KVM_CAP_USER_NMI

KVM: Unconditionally export KVM_CAP_USER_NMI

The idea between capabilities and the KVM_CHECK_EXTENSION ioctl is that
userspace can, at run-time, determine if a feature is supported or not.
This allows KVM to being supporting a new feature with a new kernel
version without any need to update user space.  Unfortunately, since the
definition of KVM_CAP_USER_NMI was guarded by #ifdef
__KVM_HAVE_USER_NMI, such discovery still required a user space update.

Therefore, unconditionally export KVM_CAP_USER_NMI and change the
the typo in the comment for the IOCTL number definition as well.

Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit 44b5ce73c99c389817be71b9161bceb197d40ecb)
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>