MdePkg: Create GetRandomNumber128 in RngLib

MdePkg: Create GetRandomNumber128 in RngLib

Declare GetRandomNumber128 in RngLib.h.
Create GetRandomNumber128 in BaseRngLib, which is simply calling
GetRandomNumber64 twice.

A GetRandomNumber128 function allows platforms with 128bit HWRNGs to
save on IO overhead that comes from having to prime the HWRNG device
before each read operation.
Using the HWRNG installed on the HP ProLiant m400 moonshot cartridge,
this will save about 50ms per RAW Entropy operation as compared with
calling GetRandomNumber64 twice.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Thomas Palmer <thomas.palmer@hpe.com>
Reviewed-by: Samer El-Haj-Mahmoud <elhaj@hpe.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>
Reviewed-by: Chao Zhang <chao.b.zhang@intel.com>
Reviewed-by: Qin Long <qin.long@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18590 6f19259b-4bc3-4df7-8a09-765794883524