blk-mq: simplify blk_mq_hw_sysfs_cpus_show()

Now that we have a cpu mask of CPUs that are mapped to
a specific hardware queue, we can just iterate that to
display the sysfs num-hw-queue/cpu_list file.

Signed-off-by: Jens Axboe <axboe@fb.com>

diff --cc block/blk-mq-sysfs.c
Simple merge