disas/nanomips: Remove Pool tables from the class

disas/nanomips: Remove Pool tables from the class

Pool tables are no longer declared as static fields of the NMD
class but as global static const variables. Pool struct is defined
outside of the class.

The NMD::Disassemble method is using the MAJOR Pool table variable, so
its implementation is moved to the end of the nanomips.cpp file,
right after the initialization of the MAJOR Pool table.

Signed-off-by: Milica Lazarevic <milica.lazarevic@syrmia.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220912122635.74032-9-milica.lazarevic@syrmia.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>