The ptp_ocp_get_mem() function does not return NULL, it returns error
pointers.
Fixes: 773bda964921 ("ptp: ocp: Expose various resources on the timecard.")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
        if (!ext)
                return -ENOMEM;
 
-       err = -EINVAL;
        ext->mem = ptp_ocp_get_mem(bp, r);
-       if (!ext->mem)
+       if (IS_ERR(ext->mem)) {
+               err = PTR_ERR(ext->mem);
                goto out;
+       }
 
        ext->bp = bp;
        ext->info = r->extra;
        void __iomem *mem;
 
        mem = ptp_ocp_get_mem(bp, r);
-       if (!mem)
-               return -EINVAL;
+       if (IS_ERR(mem))
+               return PTR_ERR(mem);
 
        bp_assign_entry(bp, r, mem);