ramips: add support for Blueendless Kimax U35WF

Blueendless Kimax U35WF is a 3,5" HDD Enclosure with Wi-Fi and Ethernet

Patch rewritten from: https://forum.openwrt.org/viewtopic.php?id=66908
Based on: https://github.com/lede-project/source/pull/965

Specification:
- SoC: MediaTek MT7620N
- CPU/Speed: 580 MHz
- Flash-Chip: KH25L12835F Spi Flash
- Flash size: 16 MiB
- RAM: 64 MiB
- LAN: 1x 100 Mbps Ethernet
- WiFi SoC-integrated: 802.11bgn
- 1x USB 2.0
- UART: for serial console

Installation:
1. Download sysupgrade.bin
2. Open vendor web interface
3. Choose to upgrade firmware
3. After reboot connect via ethernet at 192.168.1.1

Signed-off-by: Ademar Arvati Filho <arvati@hotmail.com>

target/linux/ramips/base-files/lib/upgrade/platform.sh

@@ -83,6 +83,7 @@ platform_check_image() {
 	jhr-n825r|\
 	jhr-n926r|\
 	k2p|\
+	kimax,u35wf|\
 	kn|\
 	kn_rc|\
 	kn_rf|\