qed: Prevent warning without CONFIG_RFS_ACCEL

After removing the PTP related initialization from slowpath start,
the remaining PTT entry is required only in case CONFIG_RFS_ACCEL is set.
Otherwise, it leads to a warning due to it being unused.

Fixes: d179bd16 ("qed: Acquire/release ptt_ptp lock when enabling/disabling PTP")
Signed-off-by: Yuval Mintz <Yuval.Mintz@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>