net: ip: Add cloning of missing attributes

A few attributes isn't cloned togerder with pkt.
This commit add missing part.
Additionally, because the `eof` flag in net_pkt structure is
avilable unconditionally hence `#if defined(CONFIG_NET_SOCKETS)`
guard has been removed form setter and getter functions for
this flag.

Signed-off-by: Marcin Gasiorek <marcin.gasiorek@nordicsemi.no>