misc: cxl: Fix possible null pointer dereference

It is not safe to dereference an object before a null test. It is
not needed and just remove them. Ftrace can be used instead.

Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Acked-by: Frederic Barrat <fbarrat@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>