e1d: Use HAVE_E1D in C source, not ENABLE_E1D

The config.h files contains HAVE_E1D.

Change-Id: Ib7d2db6703300b7d537c78ad9285948673d8b1d3
diff --git a/src/e1_input.c b/src/e1_input.c
index cb1612d..f27b2bb 100644
--- a/src/e1_input.c
+++ b/src/e1_input.c
@@ -890,7 +890,7 @@
 #ifdef HAVE_DAHDI_USER_H
 	e1inp_dahdi_init();
 #endif
-#ifdef ENABLE_E1D
+#ifdef HAVE_E1D
 	e1inp_e1d_init();
 #endif
 	e1inp_ipaccess_init();