ipmi: add back call to is_method_error
ipmi: add back call to is_method_error

Before reading the message, check if there's an error.  The bus call
will fail dramatically but differently than the message.

Change-Id: I3ab54cc4a4590e0cf5f3eb15dcbf045a7b8bd075
Signed-off-by: Patrick Venture <36c53fa43f47f3fd67cb2fc38031827244d18a1f@google.com>

openbmc/phosphor-pid-control,openbmc/phosphor-pid-control