Turn off led when exiting the app

[keriati]

Right now the led stays turned on after I exit the app.

I think adding

furi_hal_light_set(LightRed | LightGreen | LightBlue, 0);

around

flipper-dcf77/dcf77_app.c

Line 434 in 588bcf7

Would do it.

PS: It didn't work with my Auriol AFT 77 A1 sadly.

[schmiernippel]

Would be really nice to fix it....
For me the app works nice, thanks for that!!! :-)