commit b76b51ba upstream.

Add more debug info for EC transaction debugging, like the interrupt
status register value, the detail info of a EC transaction.
Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>