s390x/tcg: check for AFP-register, BFP and DFP data exceptions

With the annotated functions, we can now easily check this at a central
place.

DXC 1 is to be injected if an AFP register is used (for a HFP AND FPS
instruction) when AFP is disabled.
DXC 2 is to be injected if a BFP instruction is used when AFP is
disabled.
DXC 3 is to be injected if a DFP instruction is used when AFP is
disabled.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20180927130303.12236-7-david@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>