tplink-safeloader: Add support for Mercusys MR70X

tplink-safeloader: Add support for Mercusys MR70X

Add support for Mercusys MR70X image creation.

Software version:
soft_ver:1.0.3 Build 20201222 Rel. 50381

Partition table:
00000000 00040000 fs-uboot
00040000 00400000 os-image
00440000 00b60000 file-system
00fa0000 00000200 default-mac
00fa0200 00000100 pin
00fa0300 00000100 device-id
00fa0400 0000fc00 product-info
00fb0000 00008000 default-config
00fb8000 00008000 ap-def-config
00fc0000 0000c000 user-config
00fcc000 00004000 certificate
00fd0000 00008000 ap-config
00fd8000 00008000 router-config
00fe0000 00000800 partition-table
00fe0800 00000100 soft-version
00fe0900 00000200 support-list
00fe0b00 00003000 profile
00fe3b00 00000100 extra-para
00ff0000 00010000 radio

os-image and file-system is merged for dynamic split.

Signed-off-by: Yoonji Park <koreapyj@dcmys.kr>