Start implementing padding kernel

include/kernels/padding.cuh

@@ -0,0 +1,13 @@
+#ifndef PADDING_H
+#define PADDING_H
+
+__global__ void pad_matrix_kernel(
+    const float* d_input,
+    float*       d_padded,
+    int          w,
+    int          h,
+    int          n,
+    int          p
+);
+
+#endif  // PADDING_H