memstick/ms_block: Add check for alloc_ordered_workqueue

As the alloc_ordered_workqueue may return NULL pointer, it should be better
to add check for the return value. Moreover, the msb->io_queue should be
freed if error occurs later.

Fixes: 0ab30494

 ("memstick: add support for legacy memorysticks")
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Link: https://lore.kernel.org/r/20221126012558.34374-1-jiasheng@iscas.ac.cn


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>