riscv: Add header include guards to insn.h

Add header include guards to insn.h to prevent repeating declaration of
any identifiers in insn.h.

Fixes: edde558 ("riscv: Add SW single-step support for KDB")
Signed-off-by: Liao Chang <liaochang1@huawei.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Fixes: c9c1af3 ("RISC-V: rename parse_asm.h to insn.h")
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230129094242.282620-1-liaochang1@huawei.com
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Author: Liao Chang

arch/riscv/include/asm/insn.h

@@ -3,6 +3,9 @@
  * Copyright (C) 2020 SiFive
  */
 
+#ifndef _ASM_RISCV_INSN_H
+#define _ASM_RISCV_INSN_H
+
 #include <linux/bits.h>
 
 #define RV_INSN_FUNCT3_MASK	GENMASK(14, 12)
@@ -375,3 +378,4 @@ static inline void riscv_insn_insert_utype_itype_imm(u32 *utype_insn, u32 *itype
 	*utype_insn |= (imm & RV_U_IMM_31_12_MASK) + ((imm & BIT(11)) << 1);
 	*itype_insn |= ((imm & RV_I_IMM_11_0_MASK) << RV_I_IMM_11_0_OPOFF);
 }
+#endif /* _ASM_RISCV_INSN_H */