s390x/misc_helper.c: wrap IO instructions in BQL

Helpers that can trigger IO events (including interrupts) need to be
protected by the BQL. I've updated all the helpers that call into an
ioinst_handle_* functions.

Reported-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
