net/mlx5e: XDP, Drop fragmented packets larger than MTU size

XDP transmits fragmented packets that are larger than MTU size instead of
dropping those packets. The drop check that checks whether a packet is larger
than MTU is comparing MTU size against the linear part length only.

Adjust the drop check to compare MTU size against both linear and non-linear
part lengths to avoid transmitting fragmented packets larger than MTU size.

Fixes: 39a1665d ("net/mlx5e: Implement sending multi buffer XDP frames")
Signed-off-by: Carolina Jubran <cjubran@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>