target/mips: Restrict mmu_init() to TCG

mmu_init() is only required by TCG accelerator.
Restrict its declaration and call to TCG.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20210428170410.479308-21-f4bug@amsat.org>
3 files changed