net/mlx5e: Initialize on stack link modes bitmap

net/mlx5e: Initialize on stack link modes bitmap

BugLink: https://bugs.launchpad.net/bugs/1852111
[ Upstream commit 926b37f76fb0a22fe93c8873c819fd167180e85c ]

Initialize link modes bitmap on stack before using it, otherwise the
outcome of ethtool set link ksettings might have unexpected values.

Fixes: 4b95840a6ced ("net/mlx5e: Fix matching of speed to PRM link modes")
Signed-off-by: Aya Levin <ayal@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>