AK120 v1.42

[Warning]
Before firmware upgrade :
1. Make sure of your AK120’s battery level at least over 50%.
2. Make sure of your AK120’s memory size at least over 50 MB.
3. Don't remove the connection between PC & AK120 while transferring hex data.

[Newly added or revised function]
1. Time Display of MP3 file encoded with VBR is improved.
2. When pressing rewind button after 3 sec with gapless on, wrong information display issue is revised.
3. Bitrate Size issue is improved.
4. Freezing issue while playing the long title, is revised.
5. Some kind of DSD file play is stabilized.