ibmvnic: Remove code to request error information

When backing device firmware reports an error, it provides an
error ID, which is meant to be queried for more detailed error
information. Currently, however, an error ID is not provided by
the Virtual I/O server and there are not any plans to do so. For
now, it is always unfilled or zero, so request_error_information
will never be called.  Remove it.

Signed-off-by: Thomas Falcon <tlfalcon@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>