lib/accel: change max batch size to match idxd batch max

0x10 is thought to be a more common size, hard to tell until
we get real silicon but either way 0x80 limited the total
number of outstanding batches way too much.

Signed-off-by: paul luse <paul.e.luse@intel.com>
Change-Id: I61ba219b9d0185b126d300468ddd8a2214ed284a
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/4971


Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>