ppc64: add missing include in semaphore.c

arch/ppc64/kernel/semaphore.c

@@ -19,6 +19,7 @@
 #include <linux/sched.h>
 #include <asm/atomic.h>
 #include <asm/semaphore.h>
+#include <asm/errno.h>
 
 /*
  * Atomically update sem->count.