liquidio: remove PTP support in 23XX adapters

liquidio driver incorrectly indicates that PTP is supported in 23XX
adapters; this patch fixes that.  PTP is supported in 66XX and 68XX
adapters, and the driver correctly indicates that.

Signed-off-by: Prasad Kanneganti <prasad.kanneganti@cavium.com>
Signed-off-by: Felix Manlunas <felix.manlunas@cavium.com>
Signed-off-by: Derek Chickles <derek.chickles@cavium.com>
Signed-off-by: Satanand Burla <satananda.burla@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>