ipmi: Convert from tasklet to BH workqueue

The only generic interface to execute asynchronously in the BH context is
tasklet; however, it's marked deprecated and has some design flaws. To
replace tasklets, BH workqueue support was recently added. A BH workqueue
behaves similarly to regular workqueues except that the queued work items
are executed in the BH context.

This patch converts drivers/char/ipmi/* from tasklet to BH workqueue.

Based on the work done by Tejun Heo <tj@kernel.org>
Branch: https://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git

 for-6.10

Signed-off-by: Allen Pais <allen.lkml@gmail.com>
Message-Id: <20240327160314.9982-7-apais@linux.microsoft.com>
[Removed a duplicate include of workqueue.h]
Signed-off-by: Corey Minyard <minyard@acm.org>