patch 8.2.4241: some type casts are redundant

Problem:    Some type casts are redundant.
Solution:   Remove the type casts. (closes #9643)
diff --git a/src/option.c b/src/option.c
index f6b6afa..bb952fe 100644
--- a/src/option.c
+++ b/src/option.c
@@ -3702,7 +3702,7 @@
     {
 	if (errbuf != NULL)
 	{
-	    vim_snprintf((char *)errbuf, errbuflen,
+	    vim_snprintf(errbuf, errbuflen,
 			       _(e_need_at_least_nr_lines), min_rows());
 	    errmsg = errbuf;
 	}
@@ -3712,7 +3712,7 @@
     {
 	if (errbuf != NULL)
 	{
-	    vim_snprintf((char *)errbuf, errbuflen,
+	    vim_snprintf(errbuf, errbuflen,
 			    _(e_need_at_least_nr_columns), MIN_COLUMNS);
 	    errmsg = errbuf;
 	}