Merge ipmi patches from Corey Minyard:
"These have been in linux-next for a while, ready for 3.18"
* emailed patches from Corey Minyard <minyard@acm.org>:
ipmi: Clear drvdata when interface is removed
ipmi: work around gcc-4.9 build warning
ipmi/of: Don't use unavailable interfaces
ipmi: Clean up the error handling for channel config errors