UefiCpuPkg/Include: Expand description of AcpiCpuData.h structures

UefiCpuPkg/Include: Expand description of AcpiCpuData.h structures

Provide a more detailed description of each field of the
ACPI_CPU_DATA and CPU_REGISTER_TABLE structures.

Cc: Laszlo Ersek <lersek@redhat.com>
Cc: "Yao, Jiewen" <jiewen.yao@intel.com>
Cc: "Fan, Jeff" <jeff.fan@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Michael Kinney <michael.d.kinney@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Laszlo Ersek <lersek@redhat.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18950 6f19259b-4bc3-4df7-8a09-765794883524