bnxt_en: Fix PTP capability discovery

The current PTP initialization logic does not account for firmware
reset that may cause PTP capability to change.  The valid pointer
bp->ptp_cfg is used to indicate that the device is capable of PTP
and that it has been initialized.  So we must clean up bp->ptp_cfg
and free it if the firmware after reset does not support PTP.

Fixes: 93cb62d9 ("bnxt_en: Enable hardware PTP support")
Cc: Richard Cochran <richardcochran@gmail.com>
Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -7574,8 +7574,12 @@ static int __bnxt_hwrm_func_qcaps(struct bnxt *bp)
 		bp->flags &= ~BNXT_FLAG_WOL_CAP;
 		if (flags & FUNC_QCAPS_RESP_FLAGS_WOL_MAGICPKT_SUPPORTED)
 			bp->flags |= BNXT_FLAG_WOL_CAP;
-		if (flags & FUNC_QCAPS_RESP_FLAGS_PTP_SUPPORTED)
+		if (flags & FUNC_QCAPS_RESP_FLAGS_PTP_SUPPORTED) {
 			__bnxt_hwrm_ptp_qcfg(bp);
+		} else {
+			kfree(bp->ptp_cfg);
+			bp->ptp_cfg = NULL;
+		}
 	} else {
 #ifdef CONFIG_BNXT_SRIOV
 		struct bnxt_vf_info *vf = &bp->vf;