drm/omap: DISPC: Fix field order for HDMI

Interlace field order is different between VENC and HDMI. The driver
currently sets the field order for VENC.

This patch adds the code to set the field order for HDMI.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>