net: remove redundant code in dev_hard_start_xmit()

This reverts commit 068a2de57ddf4f4 (net: release dst entry while
cache-hot for GSO case too)

Before GSO packet segmentation, we already take care of skb->dst if it
can be released.

There is no point adding extra test for every segment in the gso loop.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Krishna Kumar <krkumar2@in.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>