target/filesystem: Add partprobe after parted

Partprobe is a program that informs the operating system kernel
of partition table changes, by requesting that the operating system
re-read the partition table. For instance, if you create a new
partition on one of your disks using parted, you should run
partprobe afterwards to make the kernel aware of the new partition
configuration.

This is useful for issue #799.And it's compatible with other systems.

Change-Id: Icd4c85193bd9d9e6c2b32b8463e75c7a6ff06f34
Signed-off-by: yidong0635 <dongx.yi@intel.com>
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/457735


Reviewed-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>
Reviewed-by: Paul Luse <paul.e.luse@intel.com>
Reviewed-by: Changpeng Liu <changpeng.liu@intel.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>