patch 8.2.4043: using int for second argument of ga_init2()

Problem:    Using int for second argument of ga_init2().
Solution:   Remove unnessary type cast (int) when using sizeof().
diff --git a/src/fileio.c b/src/fileio.c
index c33625a..1fcf0d9 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -4774,7 +4774,7 @@
     struct dirent	*dp;
 # endif
 
-    ga_init2(gap, (int)sizeof(void *), 20);
+    ga_init2(gap, sizeof(void *), 20);
 
 # ifdef FEAT_EVAL
 #  define FREE_ITEM(item)   do { \