quantize: use aarch64 vmaxv

quantize: use aarch64 vmaxv

Simplify max value calculation on aarch64 by using vmaxv. Much
faster for 4x4 but diminishing returns as the block size grows.

Only the vp9 quantize has a speed test hooked up. Anticipate
similar results for the other quantize versions.

Before:
[ RUN      ] NEON/VP9QuantizeTest.DISABLED_Speed/2
[    BENCH ]      Bypass calculations       4x4  31.6 ms ( ±0.0 ms )
[    BENCH ]        Full calculations       4x4  31.6 ms ( ±0.0 ms )
[    BENCH ]      Bypass calculations       8x8  17.7 ms ( ±0.0 ms )
[    BENCH ]        Full calculations       8x8  17.7 ms ( ±0.0 ms )
[    BENCH ]      Bypass calculations     16x16  14.2 ms ( ±0.0 ms )
[    BENCH ]        Full calculations     16x16  14.2 ms ( ±0.0 ms )
[       OK ] NEON/VP9QuantizeTest.DISABLED_Speed/2 (1906 ms)
[ RUN      ] NEON/VP9QuantizeTest.DISABLED_Speed/3
[    BENCH ]      Bypass calculations     32x32  18.6 ms ( ±0.0 ms )
[    BENCH ]        Full calculations     32x32  18.6 ms ( ±0.0 ms )

After:
[ RUN      ] NEON/VP9QuantizeTest.DISABLED_Speed/2
[    BENCH ]      Bypass calculations       4x4  29.1 ms ( ±0.0 ms )
[    BENCH ]        Full calculations       4x4  29.1 ms ( ±0.0 ms )
[    BENCH ]      Bypass calculations       8x8  16.9 ms ( ±0.0 ms )
[    BENCH ]        Full calculations       8x8  16.9 ms ( ±0.0 ms )
[    BENCH ]      Bypass calculations     16x16  14.1 ms ( ±0.0 ms )
[    BENCH ]        Full calculations     16x16  14.1 ms ( ±0.0 ms )
[       OK ] NEON/VP9QuantizeTest.DISABLED_Speed/2 (1803 ms)
[ RUN      ] NEON/VP9QuantizeTest.DISABLED_Speed/3
[    BENCH ]      Bypass calculations     32x32  18.6 ms ( ±0.0 ms )
[    BENCH ]        Full calculations     32x32  18.6 ms ( ±0.0 ms )

Change-Id: Ic95812b3fdbd4e47b4dcb8ed46c68a9617de38d2