svc: Move create logic to common code

Move the svc transport list logic into common transport creation code.
Refactor this code path to make the flow of control easier to read.

Move the setting and clearing of the BUSY_BIT during transport creation
to common code.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
Acked-by: Neil Brown <neilb@suse.de>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Greg Banks <gnb@sgi.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>