EmulatorPkg/PeiEmuSerialPortLib: Update the INF file Guid

EmulatorPkg/PeiEmuSerialPortLib: Update the INF file Guid

FILE GUID in PeiEmuSerialPortLib.inf is same to
MdePkg\Library\BaseSerialPortLibNull\BaseSerialPortLibNull.inf.
PeiEmuSerialPortLib.inf FILE_GUID should be updated.
https://bugzilla.tianocore.org/show_bug.cgi?id=2144

Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Andrew Fish <afish@apple.com>
Cc: Ray Ni <ray.ni@intel.com>
Signed-off-by: Shenglei Zhang <shenglei.zhang@intel.com>
Reviewed-by: Ray Ni <ray.ni@Intel.com>