[S390] remove ieee_instruction_pointer from thread_struct

The ieee_instruction_pointer can not be read from user space anymore
since git commit 613e1def6b52c399a8b72a5e11bc2e57d2546fb8, the ptrace
interface always returns zero. Remove it from the thread_struct. It
is still present in the user_regs_struct for compatability reasons.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/kernel/compat_ptrace.h b/arch/s390/kernel/compat_ptrace.h
index 123dd66..3141025 100644
--- a/arch/s390/kernel/compat_ptrace.h
+++ b/arch/s390/kernel/compat_ptrace.h
@@ -51,8 +51,7 @@
 	 * watchpoints. This is the way intel does it.
 	 */
 	per_struct32 per_info;
-	u32  ieee_instruction_pointer; 
-	/* Used to give failing instruction back to user for ieee exceptions */
+	u32  ieee_instruction_pointer;	/* obsolete, always 0 */
 };
 
 struct user32 {