CryptoPkg: Remove PcdOpensslEcEnabled from CryptoPkg.dec

CryptoPkg: Remove PcdOpensslEcEnabled from CryptoPkg.dec

Remove the PcdOpensslEcEnabled PCD that is no longer used.
The EC feature is selected by using one of the OpensslLib
instances that includes the EC features which are either
OpensslLibFull.inf or OpensslLibFullAccel.inf.

Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Xiaoyu Lu <xiaoyu1.lu@intel.com>
Cc: Guomin Jiang <guomin.jiang@intel.com>
Cc: Christopher Zurcher <christopher.zurcher@microsoft.com>
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>