MdeModulePkg AcpiTableDxe: Don't uninstall Acpi Sdt Protocol at ReadyToLock

MdeModulePkg AcpiTableDxe: Don't uninstall Acpi Sdt Protocol at ReadyToLock

1. The consumer of Acpi Sdt Protocol may want to use the API after ReadyToLock.
2. The ACPI system configuration table even could be overwritten,
   we see little issue in leaving Acpi Sdt Protocol installed.

Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Feng Tian <feng.tian@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>