wifi: iwlwifi: mei: fix tx DHCP packet for devices with new Tx API

Devices with new Tx API have the IV introduced by the HW and it is not
present in the skb at all. Hence we don't need to tell
iwl_mvm_mei_tx_copy_to_csme to jump over 8 bytes to get to the ethernet
header.

Fixes: 2da4366f ("iwlwifi: mei: add the driver to allow cooperation with CSME")
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20221030191011.12dc42133502.Idd744ffeeb84b880eb497963ee02563cbb959a42@changeid