MdeModulePkg: Add definitions for EDKII PEI ATA PassThru PPI

MdeModulePkg: Add definitions for EDKII PEI ATA PassThru PPI

REF:https://bugzilla.tianocore.org/show_bug.cgi?id=1409

This commit will add the definitions for EDKII PEI ATA PassThru PPI. This
PPI will provide services that allow ATA commands to be sent to ATA
devices attached to an ATA controller in the PEI phase.

More specifically, the PPI will provide services to:

* Send ATA commands to an ATA device (by service 'PassThru');
* Get the list of the attached ATA device on a controller (by services
  'GetNextPort' and 'GetNextDevice');
* Get the identification information (DevicePath) of the underlying ATA
  host controller (by service 'GetDevicePath').

Cc: Jian J Wang <jian.j.wang@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>