bnx2x: Enable PTP only on the PF that initializes the port

There will be only one PHC clock per port. PTP should be enabled only on
one PF per port. The change enables PTP functionality on the PF that
initializes the port. The change is useful in multi-function modes e.g.,
NPAR where a port can have more than one PF.

Signed-off-by: Sudarsana Reddy Kalluru <Sudarsana.Kalluru@cavium.com>
Signed-off-by: Ariel Elior <ariel.elior@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>