[][kernel][mt7988][Change config-5.4 and dtsi files to support pstore]

[Description]
Change config-5.4 and dtsi files to support pstore.

[Release-log]
N/A

Change-Id: I0fdb8b3705c31a59018718f03e8d81fe7418a2c2
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/7192565
2 files changed