UefiCpuPkg/MpInitLib: Properly cast from PCD to SEV-ES jump table pointer

UefiCpuPkg/MpInitLib: Properly cast from PCD to SEV-ES jump table pointer

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3385

A VS2012 build fails with a cast conversion warning when the SEV-ES work
area PCD is cast as a pointer to the SEV_ES_AP_JMP_FAR type.

When casting from a PCD value to a pointer, the cast should first be done
to a UINTN and then to the pointer. Update the code to perform a cast to
a UINTN before casting to a pointer to the SEV_ES_AP_JMP_FAR type.

Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Fixes: 7b7508ad784d16a5208c8d12dff43aef6df0835b
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Message-Id: <c89bc819856d448360430c32cb3833a9667f987b.1620656694.git.thomas.lendacky@amd.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>