target: Use array_zalloc for tpg_lun_list

Turns an order-10 allocation into slab-sized ones, thereby preventing
allocation failures with memory fragmentation.

This likely saves memory as well, as the slab allocator can pack objects
more tightly than the buddy allocator.

Signed-off-by: Joern Engel <[email protected]>
Signed-off-by: Nicholas Bellinger <[email protected]>
4 files changed