MdeModulePkg: Don't build VarCheckUefiLib and DxeCore for EBC arch

MdeModulePkg: Don't build VarCheckUefiLib and DxeCore for EBC arch

EBC build failure is caused by d7a09cb86a0416c099fa3a9e0fbe2c8f399b28de.
It changes MAX_UINTN and MAX_ADDRESS definition as below. VarCheckUefiLib
and DxeCore uses MAX_UINTN and MAX_ADDRESS in the global data initialization.
New style has >> operator, and not supported by EBC compiler.
The fix is not to build VarCheckUefiLib and DxeCore for EBC arch.

#define MAX_UINTN  ((UINTN) ~0)
==>
#define MAX_UINTN  ((UINTN)(~0ULL >> (64 - sizeof (INTN) * 8)))

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>