audio/player: Fix overflowing position

audio/player: Fix overflowing position

The position should stop at UINT32_MAX after that the progress can no
longer be calculated, this should also prevent the position to change
when the remote stack doesn't support it which is also indicated with
UINT32_MAX which apparently is the case of Spotify on Android 4.3:

[CHG] Player /org/bluez/hci0/dev_XX_XX_XX_XX_XX_XX/player0 Position: 0xffffffff
[CHG] Player /org/bluez/hci0/dev_XX_XX_XX_XX_XX_XX/player0 Status: playing
[CHG] Player /org/bluez/hci0/dev_XX_XX_XX_XX_XX_XX/player0 Position: 0x000000