Revert DSCP update changes.

Revert DSCP update changes.

This reverts commit cd8fca2ba0a7d036da069a4484d501bdc7a6f611 (jsonrpc:
Correctly setting the dscp value before reconnect.) and commit
b2e18db292cd4962af3248f11e9f17e6eaf9c033 (No need to restart DB / OVS on
changing dscp value.), which on some systems causes numerous unit test
failures that valgrind diagnoses as:

Conditional jump or move depends on uninitialised value(s)
   at 0x805F63F: jsonrpc_session_set_dscp (jsonrpc.c:1061)
   by 0x804F45D: ovsdb_jsonrpc_server_set_remotes (jsonrpc-server.c:417)
   by 0x804B775: reconfigure_from_db (ovsdb-server.c:656)
   by 0x804C231: main (ovsdb-server.c:159)

Signed-off-by: Ben Pfaff <blp@nicira.com>