staging: lustre: obdclass: Use IS_ERR_OR_NULL

Use macro IS_ERR_OR_NULL in place of tests for NULL and IS_ERR.

The Coccinelle semantic patch used to make the change is as follows:

//<smpl>
@@
expression e;
@@

- e == NULL || IS_ERR(e)
+ IS_ERR_OR_NULL(e)
//</smpl>

Signed-off-by: Amitoj Kaur Chawla <amitoj1606@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>