r210enc.c: Simplify and never store more than 10 bits.

The r10k and avrp decoders would previously store 12 bit precision
for the blue channel, which is inconsistent and probably not a
desirable behaviour.
Now the 2 unused extra bits are set to 0.
This is possibly not ideal either as RGBA1010102 format has the same
layout but stores alpha in these bits, thus explicitly setting them
to 1 might be preferable.
Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>

libavcodec/r210enc.c

@@ -58,11 +58,11 @@ static int encode_frame(AVCodecContext *avctx, AVPacket *pkt,
             uint32_t pixel;
             uint16_t r = *src++ >> 6;
             uint16_t g = *src++ >> 6;
-            uint16_t b = *src++ >> 4;
+            uint16_t b = *src++ >> 6;
             if (avctx->codec_id == AV_CODEC_ID_R210)
-                pixel = (r << 20) | (g << 10) | b >> 2;
+                pixel = (r << 20) | (g << 10) | b;
             else
-                pixel = (r << 22) | (g << 12) | b;
+                pixel = (r << 22) | (g << 12) | (b << 2);
             if (avctx->codec_id == AV_CODEC_ID_AVRP)
                 bytestream_put_le32(&dst, pixel);
             else