1. The original firmware could be found here.
2. Extract the firmware file mr10uv1.bin from TL-MR10U_V1_130321.rar
3. Download the firmware to TL-MR10U

cd /tmp
wget http://YourHttpServer/mr10uv1.bin

HttpFileServer is recommanded for file transfer.
4. Remove the boot part.

dd if=mr10uv1.bin of=tplink.bin skip=257 bs=512

Without this you will got a [e]Failed to erase block message in the next step and you will brick your device after reboot it.
5. Flash

mtd -r write /tmp/tplink.bin firmware

More information please refer to generic.uninstall
and tl-wr1043nd back.to .original.firmware