drm/omap: video-pll: add missing data for clkout2 & 3

Video pll hw data is missing bitfield definitions for clkout2 and
clkout3. We don't use those clkouts at the moment, so this has not
caused any issues.

Add the bitfields.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>