mmc: JZ4740: Add support for JZ4775

Add support for the variant on the JZ4775 SoC from Ingenic. Let's also
clarify that the drive clock selection and sample clock selection have been
supported since JZ4775, not X1000. So, support for these two functions has
been added for JZ4775 and JZ4780.

Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
Acked-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/1623329930-14387-3-git-send-email-zhouyanjie@wanyeetech.com


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>