vhost: bump SPDK_VHOST_IOVS_MAX to 129

Currently we test up to 512KB I/O sizes, and this I/O
size could fragment to 129 IOVs if split on 4KB
boundaries if the buffer start is not 4KB aligned.

This is likely the cause of a recent slew of failures
in the test pool which coincide with updating to
fio 3.3.

Signed-off-by: Jim Harris <james.r.harris@intel.com>
Change-Id: I189157af578e75e025ca8e3420712739e604fca7

Reviewed-on: https://review.gerrithub.io/395872


Reviewed-by: Daniel Verkamp <daniel.verkamp@intel.com>
Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>