fsi: occ: Store the SBEFIFO FFDC in the user response buffer

fsi: occ: Store the SBEFIFO FFDC in the user response buffer

If the SBEFIFO response indicates an error, store the response in the
user buffer and return an error. Previously, the user had no way of
obtaining the SBEFIFO FFDC.

The user's buffer now contains data in the event of a failure. No change
in the event of a successful transfer.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Link: https://lore.kernel.org/r/20211019205307.36946-3-eajames@linux.ibm.com
Signed-off-by: Joel Stanley <joel@jms.id.au>