Merge remote-tracking branch 'remotes/jnsnow/tags/ide-pull-request' into staging

# gpg: Signature made Mon Mar 23 16:51:45 2015 GMT using RSA key ID AAFC390E
# gpg: Can't check signature: public key not found

* remotes/jnsnow/tags/ide-pull-request:
  ahci-test: improve rw buffer patterns
  ahci: Fix sglist offset manipulation for BE machines
  ide: fix cmd_read_pio when nsectors > 1
  ide: fix cmd_write_pio when nsectors > 1

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