ipmi:ssif: Add check for kstrdup

Add check for the return value of kstrdup() and return the error
if it fails in order to avoid NULL pointer dereference.

Fixes: c4436c91

 ("ipmi_ssif: avoid registering duplicate ssif interface")
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Message-Id: <20230619092802.35384-1-jiasheng@iscas.ac.cn>
Signed-off-by: Corey Minyard <minyard@acm.org>