net: freescale: fix potential null pointer dereference

[ Upstream commit 06d2d6431bc8d41ef5ffd8bd4b52cea9f72aed22 ]

Add NULL check before dereferencing pointer _id_ in order to avoid
a potential NULL pointer dereference.

Addresses-Coverity-ID: 1397995
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>