ggml: Correct SVE implementation in ggml_vec_dot_f16_unroll (#16518)

The previous SVE implementation for `ggml_vec_dot_f16_unroll` contained a bug due to a copy-paste error. The wrong variable was used in an FMA instruction, leading to incorrect results. This commit corrects the variable usage and improves the clarity of the code by renaming variables to avoid confusion.

Co-authored-by: Aaron <shelhamer.aaron@gmail.com>

ggml/src/ggml-cpu/vec.h

@@ -144,14 +144,14 @@ inline static void ggml_vec_dot_f16_unroll(const int n, const int xs, float * GG
         for (int i = 0; i < np; i += ggml_f16_step) {
             ay1 = GGML_F16x_VEC_LOAD(y + i + 0 * ggml_f16_epr, 0); // 8 elements
 
-            ax1 = GGML_F16x_VEC_LOAD(x[0] + i + 0*ggml_f16_epr, 0); // 8 elemnst
+            ax1 = GGML_F16x_VEC_LOAD(x[0] + i + 0*ggml_f16_epr, 0); // 8 elements
             sum_00 = GGML_F16x_VEC_FMA(sum_00, ax1, ay1);     // sum_00 = sum_00+ax1*ay1
             ax1 = GGML_F16x_VEC_LOAD(x[1] + i + 0*ggml_f16_epr, 0); // 8 elements
             sum_10 = GGML_F16x_VEC_FMA(sum_10, ax1, ay1);
 
             ay2 = GGML_F16x_VEC_LOAD(y + i + 1 * ggml_f16_epr, 1); // next 8 elements
 
-            ax2 = GGML_F16x_VEC_LOAD(x[0] + i + 1*ggml_f16_epr, 1); // next 8 ekements
+            ax2 = GGML_F16x_VEC_LOAD(x[0] + i + 1*ggml_f16_epr, 1); // next 8 elements
             sum_01 = GGML_F16x_VEC_FMA(sum_01, ax2, ay2);
             ax2 = GGML_F16x_VEC_LOAD(x[1] + i + 1*ggml_f16_epr, 1);
             sum_11 = GGML_F16x_VEC_FMA(sum_11, ax2, ay2);
@@ -160,7 +160,7 @@ inline static void ggml_vec_dot_f16_unroll(const int n, const int xs, float * GG
 
             ax3 = GGML_F16x_VEC_LOAD(x[0] + i + 2*ggml_f16_epr, 2);
             sum_02 = GGML_F16x_VEC_FMA(sum_02, ax3, ay3);
-            ax1 = GGML_F16x_VEC_LOAD(x[1] + i + 2*ggml_f16_epr, 2);
+            ax3 = GGML_F16x_VEC_LOAD(x[1] + i + 2*ggml_f16_epr, 2);
             sum_12 = GGML_F16x_VEC_FMA(sum_12, ax3, ay3);
 
             ay4 = GGML_F16x_VEC_LOAD(y + i + 3 * ggml_f16_epr, 3);