Pinctrl: Ingenic: Add missing parts for JZ4770 and JZ4780.

Add mmc2 for JZ4770 and JZ4780:
According to the datasheet, both JZ4770 and JZ4780 have mmc2. But this
part of the original code is missing. It is worth noting that JZ4770's
mmc2 supports 8bit mode while JZ4780's does not, so we added the
corresponding code for both models.

Add nemc-wait for JZ4770 and JZ4780:
Both JZ4770 and JZ4780 have a nemc-wait pin. But this part of the
original code is missing.

Add mac for JZ4770:
JZ4770 have a mac. But this part of the original code is missing.

Signed-off-by: Zhou Yanjie <zhouyanjie@cduestc.edu.cn>
Reviewed-by: Paul Cercueil <paul@crapouillou.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>