riscv: kprobes: simulate c.j instruction

kprobes currently rejects c.j instruction. Implement it.

Signed-off-by: Nam Cao <namcaov@gmail.com>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Link: https://lore.kernel.org/r/6ef76cd9984b8015826649d13f870f8ac45a2d0d.1690704360.git.namcaov@gmail.com


Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>