net: tcp: Remove multiple times of nbuf_compact() call

finalize_segment() will call net_ipv4_finalize() or
net_ipv6_finalize(). Both the functions perform net_nbuf_compact().
But after finalize_segment(), net_nbuf_compact() called again, which
is unnecessary.

Change-Id: I9fab63bcc44eec87061a4b55edd5053cf6556a75
Signed-off-by: Ravi kumar Veeramally <ravikumar.veeramally@linux.intel.com>