Linux 3.18: d_invalidate can no longer return an error

d_invalidate is now defined as void and does not have
a return value to check.

Change-Id: Ief1b562db63877dde9f4a8ac4918b727a05b23bb
Reviewed-on: http://gerrit.openafs.org/11562
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: D Brashear <shadow@your-file-system.com>
Linux 3.18: key_type no longer has a match op

Structure key_type no longer has a match op, and
overriding the default matching has to be done
differently.

Our current match op doesn't do anything special so there's
no need to try to override the defaults; just remove the
assignment of .match and the associated function.

Change-Id: I0ee195e47f40688d9a71ea62a0b87a4265363f05
Reviewed-on: http://gerrit.openafs.org/11563
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: D Brashear <shadow@your-file-system.com>