h8300: fix syscall restarting

Back in commit f56141e3 ("all arches, signal: move restart_block to
struct task_struct"), all architectures and core code were changed to
use task_struct::restart_block.  However, when h8300 support was
subsequently restored in v4.2, it was not updated to account for this,
and maintains thread_info::restart_block, which is not kept in sync.

This patch drops the redundant restart_block from thread_info, and moves
h8300 to the common one in task_struct, ensuring that syscall restarting
always works as expected.

Fixes: f56141e3 ("all arches, signal: move restart_block to struct task_struct")
Link: http://lkml.kernel.org/r/1476714934-11635-1-git-send-email-mark.rutland@arm.com


Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: uclinux-h8-devel@lists.sourceforge.jp
Cc: <stable@vger.kernel.org>	[4.2+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>