version 1.4a
1. Modify SDRAM clock for stability

version 1.4
1. Rearrange booting sequence in start.S

version 1.3c
1. Set SDRAM clock to 108MHz for stability

version 1.3b
1. Fine tune bridge clock to improve WLAN performance.

version 1.3a
1. Add a feature to set UART baud rate divider for 38400 bps by checking
   CPU clock automatically.

version 1.3
1. Add a feature to auto detect 8186 chip version. If it is a new one, it
   Will take the default value for CPU clock (180M).
2. Delete the check for image size when writing into flash memory.

version 1.2
1. Turn on LED0 when entering monitor mode
2. Fix compile error for 8181 bootcode
3. When skip image header, also skip the checksum

version 1.1
1. Press the reset button to enter command mode
2. Fix the reboot crash when autoburn
3. Fix the bug of mktime and add tftp get support

version 1.0
1. Add rtl8186 demo board support
