UefiPayloadPkg: Use dummy constructor for PlatformHookLib

UefiPayloadPkg: Use dummy constructor for PlatformHookLib

The Library constructor is only used for library dependency.
So use a dummy function to make it clear instead of using an
actual function.

Cc: Ray Ni <ray.ni@intel.com>
Cc: Maurice Ma <maurice.ma@intel.com>
Cc: Benjamin You <benjamin.you@intel.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>
Signed-off-by: Guo Dong <guo.dong@intel.com>