Rock5 mainline hs400 mode fix

[amazingfate]

Description

Rock5b is using HS200 mode on mainline kernel for emmc because of stable issues. While slowing down the freq from 200000000 to 150000000 can also make HS400 stable.
Also slow down the emmc freq so that it is usable with mainline kernel.

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Please also note any relevant details for your test configuration.

• ./compile.sh kernel-dtb BOARD=rock-5b BRANCH=edge DEB_COMPRESS=xz
• ./compile.sh kernel-dtb BOARD=rock-5b BRANCH=current DEB_COMPRESS=xz

Checklist:

Please delete options that are not relevant.

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules

[amazingfate]

Patch for rock 5 itx is accepted upstream: https://patchwork.kernel.org/project/linux-rockchip/patch/[email protected]/