u-boot (Rockchip): roc-3328-cc: increase ddr4 clock rate at 800Mhz

[ilmich]

The Libre Computer roc-3328-cc has dd4 ram.
By porting these two vendor patches

libre-computer-project/libretech-u-boot@cdb523f
libre-computer-project/libretech-u-boot@7c0723f

the clock frequency is increased to 800Mhz (actually the clock frequency is 330Mhz).
this makes the system much more responsive and solves problems related to the playback of 4k streams reported by users on the forum (https://forum.libreelec.tv/thread/27677-rk3328-4k-hevc-stutter-frame-drop/).

I will try as soon as possible to understand if they can be sent upstream

[ilmich]

@Kwiboo @knaerzche please, when and if you can, would it be possible to have a review of this contribution?

[knaerzche]

@ilmich I'd say better send those patches upstream. @Kwiboo is very active at U-Boot mailing lists and can help reviewing them.

[Kwiboo]

This looks fine, and agree please send patches upstream.
Will be able to runtime test in 1-2 weeks, on one board from initial launch with Firefly v1.0 branding and a second more recent board with Libre Computer v1.3 branding.

[Kwiboo]

@ilmich I have now tested these patches on my two ROC-RK3328-CC V1.0 and V1.3 boards without issues and this can be merged.

Are you planning on sending this upstream to mainline U-Boot? If not I can send it, the unused 1866Mhz .dtsi-file is probably not needed for upstream.