Introduce decodetree structure to decode the tx79 opcodes.
Start it by moving the existing MFHI1 and MFLO1 opcodes.
Remove unnecessary comments.
As the TX79 share opcodes with the TX19/TX39/TX49 CPUs,
we introduce the decode_ext_txx9() dispatcher where we
will add the other decoders later.
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20210214175912.732946-9-f4bug@amsat.org>