[][kernel][MT7988][cpufreq][add cpufreq support to dsa rfb]

[Description]
Add cpufreq support to mt7988 dsa board
(reuse the device-tree of gsw board).

[Release-log]
N/A

Change-Id: I57791df2e9f9f4729cb2d32f734090de52c14072
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/6969209
1 file changed