select: 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/include/osmocom/core/select.h b/include/osmocom/core/select.h
index 5ca21c3..476c564 100644
--- a/include/osmocom/core/select.h
+++ b/include/osmocom/core/select.h
@@ -7,16 +7,16 @@
 #define BSC_FD_WRITE	0x0002
 #define BSC_FD_EXCEPT	0x0004
 
-struct bsc_fd {
+struct osmo_fd {
 	struct llist_head list;
 	int fd;
 	unsigned int when;
-	int (*cb)(struct bsc_fd *fd, unsigned int what);
+	int (*cb)(struct osmo_fd *fd, unsigned int what);
 	void *data;
 	unsigned int priv_nr;
 };
 
-int bsc_register_fd(struct bsc_fd *fd);
-void bsc_unregister_fd(struct bsc_fd *fd);
-int bsc_select_main(int polling);
+int osmo_fd_register(struct osmo_fd *fd);
+void osmo_fd_unregister(struct osmo_fd *fd);
+int osmo_select_main(int polling);
 #endif /* _BSC_SELECT_H */