ISDN/PPP: dynamically allocate struct ipppd, further cleanups

o Now that all the infrastructure is in place, struct ipppd can
  easily be allocated when /dev/ipppX is opened and freed
  in the destructor.
o Separate the mix of state and flags in struct ipppd::state.
  We only have three states, open, assigned and connected, and
  additionally two flags to jump out of poll(), returning POLLHUP /
  POLLIN.

drivers/isdn/i4l/isdn_common.h

@@ -47,7 +47,7 @@
 #endif
 
 #define isdn_BUG() \
-do { printk(KERN_WARNING "ISDN Bug at %s:%d\n", __FILE__, __LINE__); \
+do { printk(KERN_WARNING "ISDN BUG at %s:%d\n", __FILE__, __LINE__); \
 } while(0)
 
 #define HERE printk("%s:%d (%s)\n", __FILE__, __LINE__, __FUNCTION__)

drivers/isdn/i4l/isdn_ppp.h

@@ -26,12 +26,6 @@ isdn_ppp_frame_log(char *info, char *data, int len, int maxlen,
 int
 isdn_ppp_strip_proto(struct sk_buff *skb);
 
-#define IPPP_OPEN	0x01
-#define IPPP_CONNECT	0x02
-#define IPPP_CLOSEWAIT	0x04
-#define IPPP_NOBLOCK	0x08
-#define IPPP_ASSIGNED	0x10
-
 #define IPPP_MAX_HEADER 10