blk-mq-debugfs: Add decode for BLK_MQ_F_TAG_HCTX_SHARED

stable inclusion
from stable-5.10.9
commit 847c76518c41ba45ec02742a5d03065ebd4b3c39
bugzilla: 47457

--------------------------------

[ Upstream commit 02f938e9 ]

Showing the hctx flags for when BLK_MQ_F_TAG_HCTX_SHARED is set gives
something like:

root@debian:/home/john# more /sys/kernel/debug/block/sda/hctx0/flags
alloc_policy=FIFO SHOULD_MERGE|TAG_QUEUE_SHARED|3

Add the decoding for that flag.

Fixes: 32bc15af ("blk-mq: Facilitate a shared sbitmap per tagset")
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Acked-by: Xie XiuQi <xiexiuqi@huawei.com>