Remove unused [PcdsDynamic, PcdsDynamicEx] section.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Dong Guo <guo.dong@intel.com>
Reviewed-by: Fan, Jeff <jeff.fan@intel.com>
Reviewed-by: Ni, Ruiyu <ruiyu.ni@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15416 6f19259b-4bc3-4df7-8a09-765794883524