MdeModulePkg/CapsuleRuntimeDxe: Add RISCV64 architecture

MdeModulePkg/CapsuleRuntimeDxe: Add RISCV64 architecture

Add RISC-V in INF for building CapsuleRuntimeDxe RISCV64 image.

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2672

Signed-off-by: Abner Chang <abner.chang@hpe.com>
Co-authored-by: Gilbert Chen <gilbert.chen@hpe.com>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
Acked-by: Hao A Wu <hao.a.wu@intel.com>
Cc: Hao A Wu <hao.a.wu@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Cc: Gilbert Chen <gilbert.chen@hpe.com>