disas/riscv: Fix rdinstreth constraint

The constraint for `rdinstreth` was comparing the csr number to 0xc80,
which is `cycleh` instead. Fix this.

Author: Wladimir J. van der Laan <laanwj@gmail.com>
Signed-off-by: Michael Clark <mjc@sifive.com>

disas/riscv.c

@@ -614,7 +614,7 @@ static const rvc_constraint rvcc_rdtime[] = { rvc_rs1_eq_x0, rvc_csr_eq_0xc01, r
 static const rvc_constraint rvcc_rdinstret[] = { rvc_rs1_eq_x0, rvc_csr_eq_0xc02, rvc_end };
 static const rvc_constraint rvcc_rdcycleh[] = { rvc_rs1_eq_x0, rvc_csr_eq_0xc80, rvc_end };
 static const rvc_constraint rvcc_rdtimeh[] = { rvc_rs1_eq_x0, rvc_csr_eq_0xc81, rvc_end };
-static const rvc_constraint rvcc_rdinstreth[] = { rvc_rs1_eq_x0, rvc_csr_eq_0xc80, rvc_end };
+static const rvc_constraint rvcc_rdinstreth[] = { rvc_rs1_eq_x0, rvc_csr_eq_0xc82, rvc_end };
 static const rvc_constraint rvcc_frcsr[] = { rvc_rs1_eq_x0, rvc_csr_eq_0x003, rvc_end };
 static const rvc_constraint rvcc_frrm[] = { rvc_rs1_eq_x0, rvc_csr_eq_0x002, rvc_end };
 static const rvc_constraint rvcc_frflags[] = { rvc_rs1_eq_x0, rvc_csr_eq_0x001, rvc_end };