kdbus: Remove unreachable code from kdbus_msg_examine

kdbus: Remove unreachable code from kdbus_msg_examine

This fixes an issue pointed out with SVACE warning:

* UNREACHABLE_CODE: This statement in the source code might be unreachable
  during program execution.
    [unreachable] unreachable at linux-rpi3/ipc/kdbus/message.c:346
    [vec_size > vec_size + size (0 > ANY) is always false] vec_size >
     vec_size + size (0 > ANY) is always false at linux-rpi3/ipc/kdbus/message.c:345

Change-Id: Ia5204bbaad863f88c470e198a081fe58ffb4f208
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>