MdeModulePkg.dec: Change PCDs for status code.

MdeModulePkg.dec: Change PCDs for status code.

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2786

In order to support enable/disable report status code through memory
or serial dynamic, change the following PCDs from [PcdsFeatureFlag] to
[PcdsFixedAtBuild, PcdsPatchableInModule, PcdsDynamic, PcdsDynamicEx]:
  PcdStatusCodeUseSerial
  PcdStatusCodeUseMemory
The original plaforms can use PcdsFixedAtBuild in .dsc files to save size.

Reviewed-by: Jian J Wang <jian.j.wang@intel.com>
Cc: Hao A Wu <hao.a.wu@intel.com>
Signed-off-by: Ming Tan <ming.tan@intel.com>