metal: remove redundant casting in cross entropy ops

Author: xi-guo-0

src/ggml-metal/ggml-metal-ops.cpp

@@ -3666,12 +3666,11 @@ int ggml_metal_op_cross_entropy_loss(ggml_metal_op_t ctx, int idx) {
     GGML_TENSOR_LOCALS( int32_t, ne1, src1, ne);
     GGML_TENSOR_LOCALS(uint64_t, nb1, src1, nb);
 
-    const int64_t nclasses = ne00;
-    const int64_t nrows = ggml_nrows(src0);
+    const int32_t nrows = (int32_t) ggml_nrows(src0);
 
     ggml_metal_kargs_cross_entropy_loss args = {
-        /*.n_classes =*/ (int32_t) nclasses,
-        /*.n_rows    =*/ (int32_t) nrows,
+        /*.n_classes =*/ ne00,
+        /*.n_rows    =*/ nrows,
     };
 
     ggml_metal_pipeline_t pipeline = ggml_metal_library_get_pipeline_cross_entropy_loss(lib, op);
@@ -3704,11 +3703,10 @@ int ggml_metal_op_cross_entropy_loss_back(ggml_metal_op_t ctx, int idx) {
 
     GGML_TENSOR_LOCALS( int32_t, ne0, src0, ne);
 
-    const int64_t nclasses = ne00;
-    const int64_t nrows = ggml_nrows(src0);
+    const int32_t nrows = (int32_t) ggml_nrows(src0);
 
     ggml_metal_kargs_cross_entropy_loss_back args = {
-        /*.n_classes =*/ (int32_t) nclasses,
+        /*.n_classes =*/ ne00,
     };
 
     ggml_metal_pipeline_t pipeline = ggml_metal_library_get_pipeline_cross_entropy_loss_back(lib, op);