powerpc/sched: Remove unused TASK_SIZE_OF

This macro isn't used in Linux sched, now. Delete in
include/linux/sched.h and arch's include/asm.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211228064730.2882351-5-guoren@kernel.org

Author: guoren83

arch/powerpc/include/asm/task_size_64.h

@@ -44,11 +44,7 @@
  */
 #define TASK_SIZE_USER32 (0x0000000100000000UL - (1 * PAGE_SIZE))
 
-#define TASK_SIZE_OF(tsk)						\
-	(test_tsk_thread_flag(tsk, TIF_32BIT) ? TASK_SIZE_USER32 :	\
-						TASK_SIZE_USER64)
-
-#define TASK_SIZE TASK_SIZE_OF(current)
+#define TASK_SIZE (is_32bit_task() ? TASK_SIZE_USER32 : TASK_SIZE_USER64)
 
 #define TASK_UNMAPPED_BASE_USER32 (PAGE_ALIGN(TASK_SIZE_USER32 / 4))
 #define TASK_UNMAPPED_BASE_USER64 (PAGE_ALIGN(DEFAULT_MAP_WINDOW_USER64 / 4))