ggml : add GGML_QNT_VERSION to track quantization format changes

https://github.com/ggerganov/ggml/issues/150#issuecomment-1546625668

ggml-cuda.cu

@@ -414,7 +414,7 @@ static dequantize_mul_mat_vec_cuda_t ggml_get_dequantize_mul_mat_vec_cuda(ggml_t
         case GGML_TYPE_Q8_0:
             return dequantize_mul_mat_vec_q8_0_cuda;
         case GGML_TYPE_F16:
-            return dequantize_mul_mat_vec_q8_0_cuda;
+            return convert_mul_mat_vec_f16_cuda;
         default:
             return nullptr;
     }

ggml.h

@@ -190,6 +190,9 @@
 #define GGML_FILE_MAGIC   0x67676d6c // "ggml"
 #define GGML_FILE_VERSION 1
 
+#define GGML_QNT_VERSION        1    // bump this on quantization format changes
+#define GGML_QNT_VERSION_FACTOR 1000 // do not change this
+
 #define GGML_MAX_DIMS          4
 #define GGML_MAX_NODES         4096
 #define GGML_MAX_PARAMS        256