Enable sf warp_mv_refine_early_term at speed=1, 2

[deepa-kg]

The speed feature 'warp_mv_refine_early_term' is enabled for frames with pyramid level 3 and above for speed=1. For speed=2, it is enabled for frames with pyramid level 2 and above.

Results for RA CTC, A1 17 frames, A2 33 frames
(Anchor: 9b284ed)

speed 1

+-----+------+-------+-----+-------+---------------+
|Class|  Y   |  U    |   V  | YUV  |EncInstCount(%)|
+-----+------+-------+------+------+---------------+
| A1  | 0.03 |  0.06 | 0.05 | 0.03 | 98.5          |
| A2  | 0.02 | -0.02 |-0.06 | 0.01 | 98.4          |
+-----+------+-------+------+------+---------------+

speed 2

+-----+------+-------+-----+-------+---------------+
|Class|  Y   |  U    |   V  | YUV  |EncInstCount(%)|
+-----+------+-------+------+------+---------------+
| A1  |-0.01 | -0.22 | 0.02 |-0.02 | 98.3          |
| A2  | 0.03 |  0.22 |-0.02 | 0.04 | 98.5          |
+-----+------+-------+------+------+---------------+

STATS_CHANGED for speed=1, 2

[deepa-kg]

@yunqingwang1 @urvangjoshi Please review
/cc @vikasprasad10 @harishdm @ranjit-tulabandu @cherma-a @RemyaPrakasan @ram-mohan