Revert "[Fix][DVD/OMXPlayer] This fixes a regression introduced in 50a1d3c."

This reverts commits bb1aeb75e13adc0bdb6befb69feca44997e5552b and fdacd42bcebc4197c75a24c6ea54511b796b396e.

The fix is invalid and causes a mismatch between GUI assumed subtitle
and what the player actually is playing.
* [Fix][dvd/omxplayer] Don't store subs off if there are no (valid) subs available.

This partially reverts for omxplayer: cf602d29cc4d4a92f06617ee38503b379f58bbfc and c3acf406e6ec6b1769c350032c09c672ca7b1ab8.

This partially reverts for dvdplayer: ff0b1eba74ee903125e4196ffb672dd24cc379f5 and eee58b9b9463444d41ee93e7534032cdf4300931.
[Fix][dvd/omxplayer] Don't use messages to change the visibility of subtitles from inside player.
This fixes the invisibility of (auto selected) forced subtitles.
[Fix][dvd/omxplayer] Subtitles couldn't be turned on (manually) if there were no relevant subtitles.
[*SQUASH*]