[IA64] Cleanup HPSIM code (was: Re: Enable early console for Ski simulator)

After my last patch we have a new header file for HP simulator use.
Here's code to use it for stuff that used to have `extern' statements
inline in the code.  Functionality should not change with this patch.

Signed-off-by: Peter Chubb <peterc@gelato.unsw.edu.au>
Signed-off-by: Tony Luck <tony.luck@intel.com>

include/asm-ia64/hpsim.h

@@ -7,4 +7,10 @@ static inline int simcons_register(void) { return 1; }
 int simcons_register(void);
 #endif
 
+struct tty_driver;
+extern struct tty_driver *hp_simserial_driver;
+
+void ia64_ssc_connect_irq(long intr, long irq);
+void ia64_ctl_trace(long on);
+
 #endif