While jirl shares the same instruction format as bne etc,
it is not assembled the same. In particular, rd is printed
first not second and the immediate is not pc-relative.
Decode into the arg_rr_i structure, which prints correctly.
This changes the "offs" member to "imm", to update translate.
Reviewed-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>