8bpc loop restoration Zen 2

taskset -c 4-7,12-15 /home/bluezakm/dav1d_clang_O3_LTO_march-native/build/tests/checkasm  --test=looprestoration_8bpc --bench
checkasm: using random seed 637342657
SSE2:
 - looprestoration_8bpc.wiener [OK]
SSSE3:
 - looprestoration_8bpc.wiener [OK]
 - looprestoration_8bpc.sgr    [OK]
AVX2:
 - looprestoration_8bpc.wiener [OK]
 - looprestoration_8bpc.sgr    [OK]
checkasm: all 12 tests passed
nop: 51.8
sgr_3x3_8bpc_c: 320908.8
sgr_3x3_8bpc_ssse3: 96909.0
sgr_3x3_8bpc_avx2: 73183.4
sgr_5x5_8bpc_c: 256248.3
sgr_5x5_8bpc_ssse3: 68377.8
sgr_5x5_8bpc_avx2: 46980.0
sgr_mix_8bpc_c: 578888.3
sgr_mix_8bpc_ssse3: 159274.5
sgr_mix_8bpc_avx2: 111817.1
wiener_5tap_8bpc_c: 53642.8
wiener_5tap_8bpc_sse2: 22060.7
wiener_5tap_8bpc_ssse3: 17916.2
wiener_5tap_8bpc_avx2: 9010.6
wiener_7tap_8bpc_c: 53656.7
wiener_7tap_8bpc_sse2: 26665.1
wiener_7tap_8bpc_ssse3: 20308.9
wiener_7tap_8bpc_avx2: 10228.7