Refactor QS8 VADD[C] parameters

Rename parameters related to input from x & y to a & b to match QU8
microkernels

PiperOrigin-RevId: 385697181
diff --git a/src/qs8-vaddc/gen/minmax-avx-mul16-ld64-x16.c b/src/qs8-vaddc/gen/minmax-avx-mul16-ld64-x16.c
index 04086e7..f3f9bf3 100644
--- a/src/qs8-vaddc/gen/minmax-avx-mul16-ld64-x16.c
+++ b/src/qs8-vaddc/gen/minmax-avx-mul16-ld64-x16.c
@@ -21,8 +21,8 @@
     int8_t* output,
     const union xnn_qs8_add_minmax_params params[restrict XNN_MIN_ELEMENTS(1)]) XNN_DISABLE_TSAN
 {
-  const __m128i va_multiplier_lo = _mm_load_si128((const __m128i*) params->sse2.x_multiplier_lo);
-  const __m128i va_multiplier_hi = _mm_load_si128((const __m128i*) params->sse2.x_multiplier_hi);
+  const __m128i va_multiplier_lo = _mm_load_si128((const __m128i*) params->sse2.a_multiplier_lo);
+  const __m128i va_multiplier_hi = _mm_load_si128((const __m128i*) params->sse2.a_multiplier_hi);
   const __m128i vremainder_mask = _mm_load_si128((const __m128i*) params->sse2.remainder_mask);
   const __m128i vremainder_threshold = _mm_load_si128((const __m128i*) params->sse2.remainder_threshold);
   const __m128i vshift = _mm_cvtsi32_si128((int) params->sse2.shift);
@@ -30,7 +30,7 @@
   const __m128i voutput_min = _mm_load_si128((const __m128i*) params->sse2.output_min);
   const __m128i voutput_max = _mm_load_si128((const __m128i*) params->sse2.output_max);
 
-  __m128i vzero_point_product = _mm_cvtsi32_si128(params->sse2.y_multiplier[0] * (int32_t) *input_b);
+  __m128i vzero_point_product = _mm_cvtsi32_si128(params->sse2.b_multiplier[0] * (int32_t) *input_b);
   vzero_point_product = _mm_shuffle_epi32(vzero_point_product, _MM_SHUFFLE(0, 0, 0, 0));
   vzero_point_product = _mm_add_epi32(vzero_point_product, _mm_load_si128((const __m128i*) params->sse2.zero_point_product));
   for (; n >= 16 * sizeof(int8_t); n -= 16 * sizeof(int8_t)) {