ramips: add support for BOLT BL100

ramips: add support for BOLT BL100

BL100 is a router made by Bolt by a provider in Indonesia
The original firmware created using Mediatek SDK and kernel 2.6.36

- Chipset: MediaTek MT7620A ver 2, eco 6
- RAM: 64 MB
- Bootloader: U Boot
- Flash: Winbond W25Q128BV (16 MB)
- Ports: 2x 10/100 Ethernet, 1x RJ-11 VoIP
- Modem: Qualcomm LTE B40 (2300 Mhz) VID:05c6 PID:9026
- Wireless: Internal MT7620A (2.4 Ghz) & Mediatek MT76x2E (5.8 Ghz)
- Switch: MediaTek MT7620A built-in 5-port 10/100M switch
- Voltage: DC 12V 1A
- Antenna Port: 2x External Antenna, 2 LTE U.FL, 2 WiFi U.FL
- Serial Port: Yes, 3.3 V TTL, Baud 57600 8N1
- Buttons: Reset and WPS
- LED: 15 Total
  - 4 blue lte, 2 red lte, 1 reset, 1 power.
  - 1 wps, 1 voip, 1 wlan2, 1 wlan5, 1 lan, 1 wan, 1 wlan.

Installation via stock firmware
1. Unlock Telnet access by downloading the backup .tar.gz file
2. Change the Telnet configuration to LAN_Telnet=1
3. Import backup configuration
4. Restart the router
5. Login to telnet with username and password = admin : db40
6. Download sysupgrade binary and mtd_write to the kernel partition
`mtd_write write openwrt-bolt_bl100-squashfs-sysupgrade.bin Kernel`

Signed-off-by: Radito Wahyu <arditogits@gmail.com>