While UINTN defined for RISC-V 64 bits is UINT64, explictly using UINT64
for those variables that clearly are UINT64.
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Signed-off-by: Tuan Phan <tphan@ventanamicro.com>
Reviewed-by: Sunil V L <sunilvl@ventanamicro.com>