Introduce PcdCapsuleInRamSupport to turn on/off Capsule In Ram feature.
Platform could choose to drop CapsulePei/CapsuleX64 and not to support
Capsule In Ram.
Cc: Jian J Wang <jian.j.wang@intel.com> Cc: Hao A Wu <hao.a.wu@intel.com> Cc: Chao B Zhang <chao.b.zhang@intel.com> Signed-off-by: Wei6 Xu <wei6.xu@intel.com> Reviewed-by: Chao B Zhang <chao.b.zhang@intel.com> Acked-by: Hao A Wu <hao.a.wu@intel.com>