ethtool: fix incorrect datatype in set_eee ops

The member 'tx_lpi_timer' is defined with __u32 datatype in the ethtool
header file. Hence, we should use ethnl_update_u32() in set_eee ops.

Fixes: fd77be7b

 ("ethtool: set EEE settings with EEE_SET request")
Cc: <stable@vger.kernel.org> # 5.10.x
Cc: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: Wong Vee Khee <vee.khee.wong@linux.intel.com>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>