[][openwrt][common][bsp][Refactor dual image related patches]

[Description]
Refactor dual image related patches:
1. merge chunks.
2. Move patches to same folder

[Release-log]
N/A

Change-Id: I3f30642b70e3db85d6e25eba85454bf257484bd4
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/8823084
2 files changed