target/rx: Disassemble rx_index_addr into a string

target/rx: Disassemble rx_index_addr into a string

We were eliding all zero indexes.  It is only ld==0 that does
not have an index in the instruction.  This also allows us to
avoid breaking the final print into multiple pieces.

Reviewed-by: Yoshinori Sato <ysato@users.sourceforge.jp>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20190531134315.4109-19-richard.henderson@linaro.org>
Acked-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>