Revert "  Lock initial TCP window size to 64k (Improves network ping and output)"

This reverts commit fe542ed837f7568db9e1bdfb9cfced8795081195.
Revert " net: loopback: set default mtu to 64K"

This reverts commit 2f865bb78460b3915b2fa9867ffbbd5a8fd4ea89.