bsc: Call the RF Control interface ctrl all the way

We had the rf_ctrl_name and the rf_ctl pointer, make both use
the word ctrl.
diff --git a/openbsc/src/osmo-bsc/osmo_bsc_rf.c b/openbsc/src/osmo-bsc/osmo_bsc_rf.c
index cd64b52..6e9e027 100644
--- a/openbsc/src/osmo-bsc/osmo_bsc_rf.c
+++ b/openbsc/src/osmo-bsc/osmo_bsc_rf.c
@@ -243,7 +243,7 @@
 	return 0;
 }
 
-static int rf_ctl_accept(struct osmo_fd *bfd, unsigned int what)
+static int rf_ctrl_accept(struct osmo_fd *bfd, unsigned int what)
 {
 	struct osmo_bsc_rf_conn *conn;
 	struct osmo_bsc_rf *rf = bfd->data;
@@ -338,7 +338,7 @@
 	}
 
 	bfd->when = BSC_FD_READ;
-	bfd->cb = rf_ctl_accept;
+	bfd->cb = rf_ctrl_accept;
 	bfd->data = rf;
 
 	if (osmo_fd_register(bfd) != 0) {