staging: nvec: Handle filled up RX buffers

If no RX buffer is available in state 1, jump to state
0 again. This will produce an incredible amount of
warnings, but it is not supposed to happen anyway.

Signed-off-by: Julian Andres Klode <jak@jak-linux.org>
Acked-by: Marc Dietrich <marvin24@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>