MdePkg/BaseLib: Fix boot DxeCore hang on riscv platform

For scene of
HandOffToDxeCore()->SwitchStack(DxeCoreEntryPoint)->
InternalSwitchStack()->LongJump(),Variable HobList.Raw
will be passed (from *Context1 to register a0) to
DxeMain() in parameter *HobStart.

However, meanwhile the function LongJump() overrides
register a0 with a1 (-1)  due to commit (ea628f28e5 "RISCV: Fix
InternalLongJump to return correct value"), then cause hang.

Replacing calling LongJump() with new InternalSwitchStackAsm() to pass
addres data in register s0 to register a0 could fix this issue (just
like the solution in MdePkg/Library/BaseLib/AArch64/SwitchStack.S)

Signed-off-by: Yang Wang <wangyang@bosc.ac.cn>
Cc: Bamvor Jian ZHANG <zhangjian@bosc.ac.cn>
Cc: Andrei Warkentin <andrei.warkentin@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Sunil V L <sunilvl@ventanamicro.com>
Cc: Zhiguang Liu <zhiguang.liu@intel.com>
Reviewed-by: Ran Wang <wangran@bosc.ac.cn>
Reviewed-by: Andrei Warkentin <andrei.warkentin@intel.com>

MdePkg/Library/BaseLib/BaseLib.inf

@@ -397,6 +397,7 @@
   RiscV64/CpuPause.c
   RiscV64/MemoryFence.S             | GCC
   RiscV64/RiscVSetJumpLongJump.S    | GCC
+  RiscV64/SwitchStack.S             | GCC
   RiscV64/RiscVCpuBreakpoint.S      | GCC
   RiscV64/RiscVCpuPause.S           | GCC
   RiscV64/RiscVInterrupt.S          | GCC