mlx5en: Fix SIOCSIFCAPNV

In 4cc5d081d8c23, a change was introduced that manipulated
drv_ioctl_data->reqcap using IFCAP2 bits. This was noticed
when creating a mixed lagg with mce0 and ixl0 caused the
interfaces' txcsum caps to be disabled.

Fixes: 4cc5d081d8c23
Reviewed by: glebius
Sponsored by: Netflix
MFC After: 7 days