[PARISC] Fix uniprocessor build by dummying smp_send_all_nop()

Since irq.c uses smp_send_all_nop, we must define it for UP builds
as well. Make it a static inline so it gets optimized away. This forces
irq.c to include <asm/smp.h> though.

Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
diff --git a/include/asm-parisc/smp.h b/include/asm-parisc/smp.h
index a519195..dbdbd2e 100644
--- a/include/asm-parisc/smp.h
+++ b/include/asm-parisc/smp.h
@@ -54,7 +54,11 @@
 
 #define raw_smp_processor_id()	(current_thread_info()->cpu)
 
-#endif /* CONFIG_SMP */
+#else /* CONFIG_SMP */
+
+static inline void smp_send_all_nop(void) { return; }
+
+#endif
 
 #define NO_PROC_ID		0xFF		/* No processor magic marker */
 #define ANY_PROC_ID		0xFF		/* Any processor magic marker */