riscv: kprobes: Remove duplication of RV_EXTRACT_ITYPE_IMM

Use RV_EXTRACT_ITYPE_IMM, instead of re-implementing it in simulate_jalr().

Signed-off-by: Nam Cao <namcao@linutronix.de>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/linux-riscv/8ae34e966c312ae5cf6c09a35ddc290cce942208.1747215274.git.namcao@linutronix.de/
Signed-off-by: Paul Walmsley <pjw@kernel.org>

Author: covanam

arch/riscv/kernel/probes/simulate-insn.c

@@ -64,7 +64,7 @@ bool __kprobes simulate_jalr(u32 opcode, unsigned long addr, struct pt_regs *reg
 	 */
 	bool ret;
 	unsigned long base_addr;
-	u32 imm = (opcode >> 20) & 0xfff;
+	u32 imm = RV_EXTRACT_ITYPE_IMM(opcode);
 	u32 rd_index = RV_EXTRACT_RD_REG(opcode);
 	u32 rs1_index = RV_EXTRACT_RS1_REG(opcode);