cb_alloc() uses a function (pci_scan_slot) that will be annotated __devinit.

Annotate cb_alloc() with __ref to tell modpost to ignore this reference.
Signed-off-by: NSam Ravnborg <sam@ravnborg.org>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>