CUDA: fix FA out-of-bounds reads (llama/7479)

ggml-cuda/fattn-tile-f16.cu

@@ -83,7 +83,7 @@ static __global__ void flash_attn_tile_ext_f16(
         for (int i0 = 0; i0 < D/2; i0 += WARP_SIZE) {
             const int i = i0 + threadIdx.x;
 
-            const float2 tmp = Q_f2[j*(nb01/sizeof(float2)) + i];
+            const float2 tmp = ic0 + j < ne01 ? Q_f2[j*(nb01/sizeof(float2)) + i] : make_float2(0.0f, 0.0f);
             Q_h2[j][i] = make_half2(scale, scale) * make_half2(tmp.x, tmp.y);
         }
     }

ggml-cuda/fattn-tile-f32.cu

@@ -79,7 +79,7 @@ static __global__ void flash_attn_tile_ext_f32(
 
 #pragma unroll
         for (int i0 = 0; i0 < D; i0 += 2*WARP_SIZE) {
-            float2 tmp = Q_f2[j*(nb01/sizeof(float2)) + i0/2 + threadIdx.x];
+            float2 tmp = ic0 + j < ne01 ? Q_f2[j*(nb01/sizeof(float2)) + i0/2 + threadIdx.x] : make_float2(0.0f, 0.0f);
             Q_f[j][i0 + 0*WARP_SIZE + threadIdx.x] = tmp.x * scale;
             Q_f[j][i0 + 1*WARP_SIZE + threadIdx.x] = tmp.y * scale;
         }