KVM: Rename and add argument to check_extension

KVM: Rename and add argument to check_extension

In preparation to make the check_extension function available to VM scope
we add a struct kvm * argument to the function header and rename the function
accordingly. It will still be called from the /dev/kvm fd, but with a NULL
argument for struct kvm *.

Signed-off-by: Alexander Graf <agraf@suse.de>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit 784aa3d7fb6f729c06d5836c9d9569f58e4d05ae)
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>