[][OpenWrt Dev][nmbm: update the mtd wrapper due to lower read page API changed]

[Description]
Change the lower API of read page, to meet the requirement of the NMBN core.
Change the upper API of read, to meet the requirement of the MTD framework.

[Release-log]
N/A

Change-Id: I398098b522f315b2b90ae8e08a9d909ba342c518
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/4649345
1 file changed