llama : minor - remove explicity int64_t cast

Author: ggerganov

llama.cpp

@@ -781,7 +781,7 @@ static bool kv_cache_init(
     const int n_embd  = hparams.n_embd;
     const int n_layer = hparams.n_layer;
 
-    const int64_t n_mem      = (int64_t)n_layer*n_ctx;
+    const int64_t n_mem      = n_layer*n_ctx;
     const int64_t n_elements = n_embd*n_mem;
 
     cache.buf.resize(2u*n_elements*ggml_type_size(wtype) + 2u*MB);