vulkan: fix typos in dequant shaders

Author: remyoudompheng

ggml/src/ggml-vulkan/vulkan-shaders/dequant_iq2_s.comp

@@ -29,7 +29,7 @@ void main() {
         uint qs = data_a[ib].qs[4 * ib32 + l];
         const uint8_t sign = data_a[ib].qs[QUANT_K / 8 + 4 * ib32 + l];
         qs |= (qh << (8 - 2 * l)) & 0x300;
-        const uvec2 grid = iq2s_grid[qs & 511];
+        const uvec2 grid = iq2s_grid[qs];
         const u8vec4 grid0 = unpack8(grid.x);
         const u8vec4 grid1 = unpack8(grid.y);
         data_b[b_idx + 8 * l + 0] = D_TYPE(db[l/2] * grid0.x * ((sign & 1) != 0 ? -1.0 : 1.0));

ggml/src/ggml-vulkan/vulkan-shaders/dequant_iq3_s.comp

@@ -22,14 +22,14 @@ void main() {
     const uint b_idx = 256 * ib + 32 * is;
 
     const float d = float(data_a[ib].d);
-    const float db = d * (1 + 2 * ((data_a[ib].scales[is] >> (4 * (is % 2))) & 0xf));
+    const float db = d * (1 + 2 * ((data_a[ib].scales[is / 2] >> (4 * (is % 2))) & 0xf));
 
     // We must produce 32 values using 4 sign bytes, 1 qh byte, 8 qs bytes.
     uint qh = data_a[ib].qh[is];
     [[unroll]] for (uint l = 0; l < 8; ++l) {
         uint qs = data_a[ib].qs[8 * is + l];
         uint gidx = qs | ((qh << (8 - l)) & 256);
-        uint8_t signs = data_a[ib].signs[8 * is + l / 2] >> (4 * (l & 1));
+        uint8_t signs = data_a[ib].signs[4 * is + l / 2] >> (4 * (l & 1));
         u8vec4 grid = unpack8(iq3s_grid[gidx]);
         data_b[b_idx + 4 * l + 0] = D_TYPE(db * grid.x * ((signs & 1) != 0 ? -1.0 : 1.0));
         data_b[b_idx + 4 * l + 1] = D_TYPE(db * grid.y * ((signs & 2) != 0 ? -1.0 : 1.0));