Add documentation for the new sysfs entry that indicates whether or not
the SBE has timed out.
Signed-off-by: Eddie James <eajames@linux.ibm.com>
Link: https://lore.kernel.org/r/20211019211749.38059-2-eajames@linux.ibm.comSigned-off-by: Joel Stanley <joel@jms.id.au>