MdePkg/BaseLib: RISC-V: Add few more helper functions

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=4076

Few of the basic helper functions required for any
RISC-V CPU were added in edk2-platforms. To support
qemu virt, they need to be added in BaseLib.

Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Zhiguang Liu <zhiguang.liu@intel.com>
Cc: Daniel Schaefer <git@danielschaefer.me>
Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Acked-by: Abner Chang <abner.chang@amd.com>
Reviewed-by: Andrei Warkentin <andrei.warkentin@intel.com>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>

MdePkg/Include/Library/BaseLib.h

@@ -151,6 +151,56 @@ typedef struct {
 
 #define BASE_LIBRARY_JUMP_BUFFER_ALIGNMENT  8
 
+VOID
+RiscVSetSupervisorScratch (
+  IN UINT64
+  );
+
+UINT64
+RiscVGetSupervisorScratch (
+  VOID
+  );
+
+VOID
+RiscVSetSupervisorStvec (
+  IN UINT64
+  );
+
+UINT64
+RiscVGetSupervisorStvec (
+  VOID
+  );
+
+UINT64
+RiscVGetSupervisorTrapCause (
+  VOID
+  );
+
+VOID
+RiscVSetSupervisorAddressTranslationRegister (
+  IN UINT64
+  );
+
+UINT64
+RiscVReadTimer (
+  VOID
+  );
+
+VOID
+RiscVEnableTimerInterrupt (
+  VOID
+  );
+
+VOID
+RiscVDisableTimerInterrupt (
+  VOID
+  );
+
+VOID
+RiscVClearPendingTimerInterrupt (
+  VOID
+  );
+
 #endif // defined (MDE_CPU_RISCV64)
 
 #if defined (MDE_CPU_LOONGARCH64)