s390x/tcg: introduce and use s390_program_interrupt()

Allows to easily convert more callers of program_interrupt() and to
easily introduce new exceptions without forgetting about the cpu state
reset.

Use s390_program_interrupt() in places where we already had the same
pattern. We will later get rid of program_interrupt().

RA != 0 checks are already done behind the scenes.

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: <20171130162744.25442-2-david@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
