libqos/ahci: Add cmd response sanity check helpers

This patch adds a few helpers to help sanity-check the response of the
AHCI device after a command.

ahci_d2h_check_sanity inspects the D2H Register FIS,
ahci_pio_check_sanity inspects the PIO Setup FIS, and
ahci_cmd_check_sanity inspects the command header.

To support the PIO sanity check, a new structure is added for the
PIO Setup FIS type. Existing FIS types (H2D and D2H) have had their
members renamed slightly to condense reserved members into fewer
fields; and LBA fields are now represented by arrays of 8 byte chunks
instead of independent variables.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1423158090-25580-9-git-send-email-jsnow@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
