RISC-V: Add SSTC extension CSR details

This patch just introduces the required CSR fields related to the
SSTC extension.
Reviewed-by: NAnup Patel <anup@brainfault.org>
Signed-off-by: NAtish Patra <atishp@rivosinc.com>
Link: https://lore.kernel.org/r/20220722165047.519994-2-atishp@rivosinc.comSigned-off-by: NPalmer Dabbelt <palmer@rivosinc.com>

arch/riscv/include/asm/csr.h

@@ -235,6 +235,9 @@
 #define CSR_SIP			0x144
 #define CSR_SATP		0x180
 
+#define CSR_STIMECMP		0x14D
+#define CSR_STIMECMPH		0x15D
+
 #define CSR_VSSTATUS		0x200
 #define CSR_VSIE		0x204
 #define CSR_VSTVEC		0x205
@@ -244,6 +247,8 @@
 #define CSR_VSTVAL		0x243
 #define CSR_VSIP		0x244
 #define CSR_VSATP		0x280
+#define CSR_VSTIMECMP		0x24D
+#define CSR_VSTIMECMPH		0x25D
 
 #define CSR_HSTATUS		0x600
 #define CSR_HEDELEG		0x602