kdbus: don't unlink _synchronous_ replies

kdbus: don't unlink _synchronous_ replies

Keeping only interrupted synchronous calls linked is not enough.
If a reply comes just after the signal, before marking the reply structure
as interrupted, then the reply is unlinked and the restarted call
can't pick it up anymore.

This commit leaves all synchronous replies linked.

This way:
- non-synchronous calls work as before the changes - replies are unlinked
  by the replier in kdbus_conn_reply();
- replies for synchronous calls are unlinked by the caller in
  kdbus_conn_wait_reply().

Change-Id: If162f96a14d51d6a4475fe5c55039dc92236b19a
Signed-off-by: Adrian Szyndela <adrian.s@samsung.com>