UefiCpuPkg/CpuExceptionHandlerLib: alloc code memory for exception handlers

UefiCpuPkg/CpuExceptionHandlerLib: alloc code memory for exception handlers

If PcdDxeNxMemoryProtectionPolicy is set to enable protection for memory
of EfiBootServicesData, EfiConventionalMemory, the BIOS will reset after
timer initialized and started.

The root cause is that the memory used to hold the exception and interrupt
handler is allocated with type of EfiBootServicesData and marked as
non-executable due to NX feature enabled. This patch fixes it by allocating
EfiBootServicesCode type of memory for those handlers instead.

Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>