net: fec: struct fec_enet_private: remove obsolete comment

In commit 4d494cdc ("net: fec: change data structure to support
multiqueue") the data structures were changed, so that the comment about
the sent-in-place skb doesn't apply any more. Remove it.

Reviewed-by: Wei Fang <wei.fang@nxp.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Link: https://patch.msgid.link/20250618-fec-cleanups-v4-2-c16f9a1af124@pengutronix.de


Signed-off-by: Jakub Kicinski <kuba@kernel.org>