[SCSI] qla2xxx: T10 DIF - Fix incorrect error reporting.

This fix:
    - Disables app tag peeking; correct tag check will be added when the
      SCSI API is available.
    - Always derive ref_tag from scsi_get_lba()
    - Removes incorrect swap of FCP_LUN in FCP_CMND
    - Moves app-tag error check before ref-tag check. The reason being,
      currently there is no interface in SCSI to retrieve the app-tag
      for protection I/Os, so driver puts zero for app-tag in the
      firmware interface, but requests not to validate it, but when a
      ref-tag error is detected by firmware, it would put
      expected/actual tags for all the protection tags (guard/app/ref).
      As driver checks for app tag error first, a ref-tag error is
      incorrectly flagged as app-tag error.
    - Convert HBA specific checks to capability based.

Signed-off-by: Arun Easi <arun.easi@qlogic.com>
Signed-off-by: Chad Dupuis <chad.dupuis@qlogic.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>