mmc: core: Fix tag set memory leak

The tag set is allocated in mmc_init_queue but never freed. This results
in a memory leak. This change makes sure we free the tag set when the
queue is also freed.

Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Fixes: 81196976 ("mmc: block: Add blk-mq support")
Cc: stable@vger.kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>