Commit fd1401495b ("net/tcp: Move net_tcp_set_hdr() away from net
core") removed <net/tcp.h>. This results in a not found error being
generated when CONFIG_NET_TCP is enabled.
We also, don't need to include <net/udp.h> anymore due to new
net_pkt API changes.
Let's clean up the includes by removing both of them.
Signed-off-by: Michael Scott <mike@foundries.io>