linux-phytec-ti

net: cavium: clean up return value check in cavium_ptp_probe

ptp_clock_register never return NULL, so no need check this
in cavium_ptp_probe.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>