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/register.c b/src/register.c
index 08a73fe..d604bae 100644
--- a/src/register.c
+++ b/src/register.c
@@ -527,7 +527,7 @@
     int		j;
     char_u	*str;
 
-    ga_init2(&ga, (int)sizeof(char_u), 400);
+    ga_init2(&ga, sizeof(char_u), 400);
 
     // search backwards to find the first line of this command.
     // Any line not starting with \ or "\ is the start of the