powerpc/powernv: Add a null pointer check in opal_event_init()

stable inclusion
from stable-v4.19.306
commit 8422d179cf46889c15ceff9ede48c5bfa4e7f0b4
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9Q9IH
CVE: CVE-2023-52686

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8422d179cf46889c15ceff9ede48c5bfa4e7f0b4



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[ Upstream commit 8649829a1dd25199bbf557b2621cedb4bf9b3050 ]

kasprintf() returns a pointer to dynamically allocated memory
which can be NULL upon failure.

Fixes: 2717a33d ("powerpc/opal-irqchip: Use interrupt names if present")
Signed-off-by: Kunwu Chan <chentao@kylinos.cn>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231127030755.1546750-1-chentao@kylinos.cn


Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Guo Mengqi <guomengqi3@huawei.com>