INCOMPLATE PLANAR COLOR SUPPORT

```
Description: The original NX design included support for planar colors,
i.e,. for devices that provide separate framebuffers for each
color component. Planar graphics hard was common some years
back but is rarely encountered today. In fact, I am not aware
of any MCU that implements planar framebuffers.

Support for planar colors is, however, unverified and
incomplete. In fact, many recent changes explicitly assume a
single color plane: Planar colors are specified by a array
of components; some recent logic uses only component [0],
ignoring the possible existence of other color component frames.

Completely removing planar color support is one reasonable
options; it is not likely that NuttX will encounter planar
color hardware and this would greatly simplify the logic and
eliminate inconsistencies in the immplementation.
Status: Open
Priority: Low. There is no problem other than one of aesthetics.
```