[rbp/omxplayer] Remove clock manipulation from a/v players
[rbp/omxplayer] Move start flags out of clock component

Keep track of start flags locally. I believe the behaviour is unchanged now that clock state is controlled only by OMXPlayer.
[rbp/omxplayer] Remove unused function OMXStart
Merge pull request #2927 from popcornmix/remove_clock_manipulation

[rbp/omxplayer] Remove clock manipulation