ShellPkg/UefiShellDebug1CommandsLib: Remove the unused function CharToUpper

ShellPkg/UefiShellDebug1CommandsLib: Remove the unused function CharToUpper

CharToUpper is an unused function, so it will be removed.
https://bugzilla.tianocore.org/show_bug.cgi?id=1399

v2:Update the title.

Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Jaben Carsey <jaben.carsey@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Shenglei Zhang <shenglei.zhang@intel.com>
Reviewed-by: Jaben Carsey <jaben.carsey@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>