MdePkg/BaseCpuLib: RISC-V Base CPU library

implementation.

Implement RISC-V CPU related functions in BaseCpuLib.

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>
Reviewed-by: Zhiguang Liu <zhiguang.liu@intel.com>

Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Cc: Gilbert Chen <gilbert.chen@hpe.com>

MdePkg/Library/BaseCpuLib/RiscV/Cpu.S

@@ -0,0 +1,19 @@
+//------------------------------------------------------------------------------
+//
+// CpuSleep for RISC-V
+//
+// Copyright (c) 2020, Hewlett Packard Enterprise Development LP. All rights reserved.<BR>
+// SPDX-License-Identifier: BSD-2-Clause-Patent
+//
+//------------------------------------------------------------------------------
+.data
+.align 3
+.section .text
+
+.global ASM_PFX(_CpuSleep)
+
+ASM_PFX(_CpuSleep):
+    wfi
+    ret
+
+