input: use generic ipa_msg_recv() instead of ipaccess_read_msg()

We use the new generic function to receive messages, instead of
ipaccess_read_msg.

It's a mere renaming, but it's the first step before the rework
that will happen soon to avoid calling read() twice.
diff --git a/src/input/hsl.c b/src/input/hsl.c
index e6388c8..cb1aa51 100644
--- a/src/input/hsl.c
+++ b/src/input/hsl.c
@@ -84,8 +84,8 @@
 	struct msgb *msg;
 	int ret = 0, error;
 
-	msg = ipaccess_read_msg(bfd, &error);
-	if (!msg) {
+	error = ipa_msg_recv(bfd->fd, &msg);
+	if (error <= 0) {
 		if (e1i_ts->line->ops.error)
 			e1i_ts->line->ops.error(NULL, error);
 		if (error == 0) {