net: ethtool: copy input_xfrm to user-space in ethtool_get_rxfh

The ioctl path of ethtool's get channels is missing the final step of
copying the new input_xfrm field to user-space. This should have been
part of [1].

Link: https://lore.kernel.org/netdev/20231213003321.605376-1-ahmed.zaki@intel.com/ [1]
Fixes: 13e59344

 ("net: ethtool: add support for symmetric-xor RSS hash")
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Ahmed Zaki <ahmed.zaki@intel.com>
Link: https://lore.kernel.org/r/20231221184235.9192-2-ahmed.zaki@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>