disas/nanomips: Delete wrapper functions

disas/nanomips: Delete wrapper functions

Following functions just wrap the decode_gpr_gpr3() function:
- encode_rs3_and_check_rs3_ge_rt3()
- encode_rs3_and_check_rs3_lt_rt3()
Therefore those have been deleted. Calls to these two functions have
been replaced with calls to decode_gpr_gpr3.

Signed-off-by: Milica Lazarevic <milica.lazarevic@syrmia.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220912122635.74032-15-milica.lazarevic@syrmia.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>