sparc64: Kill off old sys_perfctr system call and state.

People should be using the perf events interfaces, and
the way these system call facilities used the %pcr conflicts
with the usage of the NMI watchdog and perf events.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/arch/sparc/include/asm/perfctr.h b/arch/sparc/include/asm/perfctr.h
index 8368730..8d8720a 100644
--- a/arch/sparc/include/asm/perfctr.h
+++ b/arch/sparc/include/asm/perfctr.h
@@ -10,8 +10,8 @@
  * from enumeration below.  The meaning of further arguments
  * are determined by the operation code.
  *
- * int sys_perfctr(int opcode, unsigned long arg0,
- *                 unsigned long arg1, unsigned long arg2)
+ * NOTE: This system call is no longer provided, use the perf_events
+ *       infrastructure.
  *
  * Pointers which are passed by the user are pointers to 64-bit
  * integers.