patch 8.2.1637: Vim9: :put ={expr} does not work inside :def function

Problem:    Vim9: :put ={expr} does not work inside :def function.
Solution:   Add ISN_PUT. (closes #6397)
diff --git a/src/ex_docmd.c b/src/ex_docmd.c
index 3dee01d..1d3cfcd 100644
--- a/src/ex_docmd.c
+++ b/src/ex_docmd.c
@@ -7321,7 +7321,7 @@
 	eap->forceit = TRUE;
     }
     curwin->w_cursor.lnum = eap->line2;
-    do_put(eap->regname, eap->forceit ? BACKWARD : FORWARD, 1L,
+    do_put(eap->regname, NULL, eap->forceit ? BACKWARD : FORWARD, 1L,
 						       PUT_LINE|PUT_CURSLINE);
 }