sh: Kill off sh64's unused alloc/free_task_struct() definitions.

These were left over from some time ago, sh64 never got around to
defining __HAVE_ARCH_TASK_STRUCT_ALLOCATOR during the conversion, and it
has no need to. Kill these off and use the generic versions instead.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

arch/sh/kernel/process_64.c

@@ -305,18 +305,6 @@ void show_regs(struct pt_regs * regs)
 	}
 }
 
-struct task_struct * alloc_task_struct(void)
-{
-	/* Get task descriptor pages */
-	return (struct task_struct *)
-		__get_free_pages(GFP_KERNEL, get_order(THREAD_SIZE));
-}
-
-void free_task_struct(struct task_struct *p)
-{
-	free_pages((unsigned long) p, get_order(THREAD_SIZE));
-}
-
 /*
  * Create a kernel thread
  */