task_work: remove legacy TWA_SIGNAL path

stable inclusion
from stable-v5.10.162
commit 61bdeb142e8f7550826373295cb35b3571d70f62
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7P7OH

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=61bdeb142e8f7550826373295cb35b3571d70f62



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[ Upstream commit 03941ccf ]

All archs now support TIF_NOTIFY_SIGNAL.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>