Fix some code style issues

Signed-off-by: Philippe De Swert <philippe.deswert@jollamobile.com>
[usb-moded] Do not pop-up ask dialog if charging mode was chosen before device locked up. Fixes: JB#13550

Track if charging mode was set explicitly, so we can decide accordingly when
devicelock asks for re-evaluation of the connection state.

Signed-off-by: Philippe De Swert <philippe.deswert@jollamobile.com>