Maintainers.txt: update it to remove IntelSiliconPkg maintainers

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=1890

Signed-off-by: Liming Gao <liming.gao@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Rangasai V Chaganty <rangasai.v.chaganty@intel.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>
Reviewed-by: Sai Chaganty <rangasai.v.chaganty@intel.com>

Maintainers.txt

@@ -151,11 +151,6 @@ M: Chasel Chiu <chasel.chiu@intel.com>
 R: Nate DeSimone <nathaniel.l.desimone@intel.com>
 R: Star Zeng <star.zeng@intel.com>
 
-IntelSiliconPkg
-W: https://github.com/tianocore/tianocore.github.io/wiki/IntelSiliconPkg
-M: Ray Ni <ray.ni@intel.com>
-M: Rangasai V Chaganty <rangasai.v.chaganty@intel.com>
-
 MdeModulePkg
 W: https://github.com/tianocore/tianocore.github.io/wiki/MdeModulePkg
 M: Jian J Wang <jian.j.wang@intel.com>