qede: Adverstise software timestamp caps when PHC is not available.

When ptp clock is not available for a PF (e.g., higher PFs in NPAR mode),
get-tsinfo() callback should return the software timestamp capabilities
instead of returning the error.

Fixes: 4c55215c

 ("qede: Add driver support for PTP")
Signed-off-by: Sudarsana Reddy Kalluru <Sudarsana.Kalluru@cavium.com>
Signed-off-by: Michal Kalderon <Michal.Kalderon@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>