disas/nanomips: Remove __cond methods from class

disas/nanomips: Remove __cond methods from class

NMD class methods with the conditional_function type like
NMD::ADDIU_32__cond, NMD::ADDIU_RS5__cond, etc. are removed from the NMD
class. They're now declared global static functions. Therefore, typedef
of the function pointer, conditional_function is defined outside of the
class.

Now that conditional_function type functions are not part of the NMD
class we can't access them using the this pointer. Thus, the use of
the this pointer has been deleted.

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: <20220912122635.74032-7-milica.lazarevic@syrmia.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>