Merge remote-tracking branch 'remotes/cohuck/tags/s390x-20160128' into staging

Mostly bugfixes and small improvements; and the gdb target.xml
patch.

# gpg: Signature made Thu 28 Jan 2016 11:02:14 GMT using RSA key ID C6F02FAF
# gpg: Good signature from "Cornelia Huck <huckc@linux.vnet.ibm.com>"
# gpg:                 aka "Cornelia Huck <cornelia.huck@de.ibm.com>"

* remotes/cohuck/tags/s390x-20160128:
  s390x: s390_cpu_get_phys_page_debug has to return -1
  gdb: provide the name of the architecture in the target.xml
  s390x/css: fix control flags during csch
  watchdog/diag288: don't reset for action=none|debug|pause
  watchdog: introduction of get_watchdog_action
  s390x: fix generation of event information crw
  s390x/ioinst: set type and len for SEI response
  s390x/sclp: add device to the sysbus in sclp_realize
  s390x/machine: make addon register fields static
  s390x/skeys: Fix instance and class size

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>