ipmi: kcs_bmc: handle devm_kasprintf() failure case

ipmi: kcs_bmc: handle devm_kasprintf() failure case

[ Upstream commit 42c7c6ef1e6fa5fc0425120f06f045190b1dda2d ]

devm_kasprintf() may return NULL if internal allocation failed so this
assignment is not safe. Moved the error exit path and added the !NULL
which then allows the devres manager to take care of cleanup.

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Fixes: cd2315d471f4 ("ipmi: kcs_bmc: don't change device name")
Signed-off-by: Corey Minyard <cminyard@mvista.com>
Reviewed-by: Haiyue Wang <haiyue.wang@linux.intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>