We check the state of an event ring or channel both before and after
any GSI command issued that will change that state.  In most--but
not all--cases, if the state is something different than expected we
report an error message.

Add error messages where missing, so that all unexpected states
provide information about what went wrong.  Drop the parentheses
around the state value shown in all cases.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>