s390x/flic: factor out injection of floating interrupts

s390x/flic: factor out injection of floating interrupts

Let the flic device handle it internally. This will allow us to later
on store floating interrupts in the flic for the TCG case.

This now also simplifies kvm.c. All that's left is the fallback
interface for floating interrupts, which is now triggered directly via
the flic in case anything goes wrong.

Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20180129125623.21729-6-david@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>