aarch64: pixel: add 10bits sad functions

aarch64: pixel: add 10bits sad functions

Provide routines for sad functions for high bit depth, i.e. 10 bits.
Benchmarks run on AWS Gravtion 2 instances.

sad_4x4_c: 583
sad_4x4_neon: 273
sad_4x8_c: 1179
sad_4x8_neon: 366
sad_4x16_c: 2121
sad_4x16_neon: 550
sad_8x4_c: 924
sad_8x4_neon: 213
sad_8x8_c: 1711
sad_8x8_neon: 316
sad_8x16_c: 3505
sad_8x16_neon: 497
sad_16x8_c: 3070
sad_16x8_neon: 635
sad_16x16_c: 6113
sad_16x16_neon: 1118

Signed-off-by: Hubert Mazur <hum@semihalf.com>
Signed-off-by: Grzegorz Bernacki <gjb@semihalf.com>