[*] frontpaneld: Fix ":" bug for stb840. Add brightness control for OLED (stb850). Changed brightness control for xx1628 controllers.

- Was fixed bug "bo:ot" when stb840 booting.
- Add brightness control for OLED (stb850), range is 0x00 - 0xFF.
- Changed brightness control for ct1628 and tm1668 controllers (now range is 0x00-0xFF).

Signed-off-by: Anton Proshutya <Anton.Proshutya@elecard.ru>
Merge branch 'master' of https://github.com/ElecardSTB/elecard-apps