OMAP2: Devkit8000: Remove en-/disable for tv panel

devkit8000_panel_enable_tv and devkit8000_panel_disable_tv are already
done in DSS2 code. So they are no longer needed in board code.

Signed-off-by: Thomas Weber <weber@corscience.de>
Signed-off-by: Tony Lindgren <tony@atomide.com>