net: sparx5: fix the maximum frame length register

[ Upstream commit ddd7ba00 ]

On port initialization, we configure the maximum frame length accepted
by the receive module associated with the port. This value is currently
written to the MAX_LEN field of the DEV10G_MAC_ENA_CFG register, when in
fact, it should be written to the DEV10G_MAC_MAXLEN_CFG register. Fix
this.

Fixes: 946e7fd5 ("net: sparx5: add port module support")
Signed-off-by: Daniel Machon <daniel.machon@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>