[][kernel][mt7988][cpufreq][change u32 variable to u8]

[Description]
Change u32 variable to u8, we only need read efuse register low 8 bit,
u8 variable is enough

[Release-log]
N/A


Change-Id: I2aaeb2b7a42183bf529a16b280bf6ce7b24aa8d0
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/6637744
Build: srv_hbgsm110
1 file changed