UefiCpuPkg/CpuDxe: Add ApEntryPointInC

UefiCpuPkg/CpuDxe: Add ApEntryPointInC

This is the function the AP assembly code will expect to call after
getting a lock and setting up the stack.

Only one AP will enter this routine at a time.

If ApEntryPointInC exits, then the assembly code will loop around to
grab the lock, setup the stack, and call ApEntryPointInC again.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Jeff Fan <jeff.fan@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16346 6f19259b-4bc3-4df7-8a09-765794883524