Merge remote-tracking branch 'remotes/xtensa/tags/20150307-xtensa' into staging

Xtensa updates:

- implement do_unassigned_access callback;
- fix ML605 xtfpga FLASH size.

# gpg: Signature made Sat Mar  7 12:35:05 2015 GMT using RSA key ID F83FA044
# gpg: Good signature from "Max Filippov <max.filippov@cogentembedded.com>"
# gpg:                 aka "Max Filippov <jcmvbkbc@gmail.com>"

* remotes/xtensa/tags/20150307-xtensa:
  target-xtensa: xtfpga: fix ml605 flash size
  target-xtensa: implement do_unassigned_access callback
  hw/xtensa: allow reads/writes in the system I/O region

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