Default was 8 which meant max of 8 bdevs. Bump it up to 64. Fixes issue #1232 Signed-off-by: paul luse <paul.e.luse@intel.com> Change-Id: I966e90de5c27910df0e4da0d1062d9d1665f8de6 Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/1063 Tested-by: SPDK CI Jenkins <sys_sgci@intel.com> Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com> Reviewed-by: Aleksey Marchuk <alexeymar@mellanox.com>