[ARM] Fix "thead" typo

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/kernel/ptrace.c

@@ -628,7 +628,7 @@ static int ptrace_setwmmxregs(struct task_struct *tsk, void __user *ufp)
 	if (!test_ti_thread_flag(thread, TIF_USING_IWMMXT))
 		return -EACCES;
 	iwmmxt_task_release(thread);  /* force a reload */
-	return copy_from_user(&thead->fpstate.iwmmxt, ufp, IWMMXT_SIZE)
+	return copy_from_user(&thread->fpstate.iwmmxt, ufp, IWMMXT_SIZE)
 		? -EFAULT : 0;
 }