kernel-doc: move ignoring kmemcheck

Somehow I managed to generate a diff that put these 2 lines
into the wrong function:  should have been in dump_struct()
instead of in dump_enum().

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>