[PATCH] nbd: Don't create all MAX_NBD devices by default all the time

This patches adds the "nbds_max" parameter to the nbd kernel module, which
limits the number of nbds allocated.  Previously, always all 128 entries
were allocated unconditionally, which used to waste resources and
needlessly flood the hotplug system with events.  (Defaults to 16 now.)

Signed-off-by: Lars Marowsky-Bree <lmb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>