MFC r307966:

MFC r307966:

Remove an extraneous call to soisconnected() in syncache_socket(),
introduced with r261242.  The useful and expected soisconnected()
call is done in tcp_do_segment().

Has been found as part of unrelated PR:212920 investigation.

Improve slightly (~2%) the maximum number of TCP accept per second.

Tested by:		kevin.bowling_kev009.com, jch
Approved by:		gnn, hiren
MFC after:		1 week
Sponsored by:		Verisign, Inc
Differential Revision:	https://reviews.freebsd.org/D8072

git-svn-id: svn://svn.freebsd.org/base/stable/10@308263 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f