patch 8.2.3930: getcmdline() argument has a misleading type

Problem:    getcmdline() argument has a misleading type.
Solution:   Use the correct type, even though the value is not used.
diff --git a/src/register.c b/src/register.c
index 6a4bc2c..2a5f119 100644
--- a/src/register.c
+++ b/src/register.c
@@ -97,7 +97,7 @@
 {
     char_u	*new_line;
 
-    new_line = getcmdline('=', 0L, 0, TRUE);
+    new_line = getcmdline('=', 0L, 0, 0);
     if (new_line == NULL)
 	return NUL;
     if (*new_line == NUL)	// use previous line