blk-mq: setup queue ->tag_set before initializing hctx

In the Linux kernel, the following vulnerability has been resolved: blk-mq: setup queue ->tag_set before initializing hctx Commit 7b815817aa58 ("blk-mq: add helper for checking if one CPU is mapped to specified hctx") needs to check queue mapping via tag set in hctx's cpuhp handler. However, q->tag_set may not be setup yet when the cpuhp handler is enabled, then kernel oops is triggered. Fix the issue by setup queue tag_set before initializing hctx.