src: use namespace prefix osmo_fd* and osmo_select*

Summary of changes:

s/struct bsc_fd/struct osmo_fd/g
s/bsc_register_fd/osmo_fd_register/g
s/bsc_unregister_fd/osmo_fd_unregister/g
s/bsc_select_main/osmo_select_main/g
diff --git a/openbsc/src/ipaccess/ipaccess-find.c b/openbsc/src/ipaccess/ipaccess-find.c
index 24f602e..b0db045 100644
--- a/openbsc/src/ipaccess/ipaccess-find.c
+++ b/openbsc/src/ipaccess/ipaccess-find.c
@@ -141,7 +141,7 @@
 	return parse_response(buf+6, len-6);
 }
 
-static int bfd_cb(struct bsc_fd *bfd, unsigned int flags)
+static int bfd_cb(struct osmo_fd *bfd, unsigned int flags)
 {
 	if (flags & BSC_FD_READ)
 		return read_response(bfd->fd);
@@ -156,7 +156,7 @@
 
 static void timer_cb(void *_data)
 {
-	struct bsc_fd *bfd = _data;
+	struct osmo_fd *bfd = _data;
 
 	bfd->when |= BSC_FD_WRITE;
 
@@ -165,7 +165,7 @@
 
 int main(int argc, char **argv)
 {
-	struct bsc_fd bfd;
+	struct osmo_fd bfd;
 	char *ifname;
 	int rc;
 
@@ -187,7 +187,7 @@
 		exit(1);
 	}
 
-	bsc_register_fd(&bfd);
+	osmo_fd_register(&bfd);
 
 	timer.cb = timer_cb;
 	timer.data = &bfd;
@@ -197,7 +197,7 @@
 	printf("Trying to find ip.access BTS by broadcast UDP...\n");
 
 	while (1) {
-		rc = bsc_select_main(0);
+		rc = osmo_select_main(0);
 		if (rc < 0)
 			exit(3);
 	}