[pvr] unify settings to control of showing channel info on channel switch

This unifies the settings 'pvrmenu.infoswitch', 'pvrmenu.infotimeout',
'pvrmenu.infotime' to one new setting 'pvrmenu.displaychannelinfo'
which holds the options 'Off' and '1 sec' to '15 sec'.
[pvr] show channel info after channel switch from within channel osd