MdePkg/BaseLib: Remove definitions of two functions

MdePkg/BaseLib: Remove definitions of two functions

InternalCharToUpper and InternalBaseLibAsciiToUpper are internal functions
and now we will introduce public functions that have the same effects.
So I remove their definitions in BaseLibInternals.h.
https://bugzilla.tianocore.org/show_bug.cgi?id=1369

Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Shenglei Zhang <shenglei.zhang@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>