i5000-edac: hold reference to mci kobject

i5000-edac: hold reference to mci kobject

It turns out that edac_mc_del_mc will kobject_put the last kref on the
mci object.

If the timing is just right, that means that the mci object is freed
before before i5000_remove_one has a chance to free the resources
associated with it, causing a null pointer exceptions when unloading the
driver.  Insert a kobject_{get,put} pair so that this doesn't happen.

Signed-off-by: Darrick J. Wong <[email protected]>
Cc: Doug Thompson <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>