PcAtChipsetPkg: new AcpiTimerLib libraries. 

  Two library instances are added to support BASE type and DXE type. Those libraries provides basic timer support using the ACPI timer hardware.  The performance  counter features are provided by the processors time stamp counter.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Gao, Liming <liming.gao@intel.com>
Reviewed-by: Kinney, Michael D <michael.d.kinney@intel.com>


git-svn-id: svn://svn.code.sf.net/p/edk2/code/trunk/edk2/PcAtChipsetPkg@15803 6f19259b-4bc3-4df7-8a09-765794883524