Partitions could be meaningful on single-drive RAID0

Partitions could be meaningful on single-drive RAID0

If we create a single-drive RAID0 array on partitioned drive,
we do not lose information about disk structure after operation
(partitions are visible on created array)
Warning message:

mdadm: partition table exists on /dev/sdX but will be lost or
       meaningless after creating array"

is not necessary during creation single-drive RAID0 array.
This patch removes the message.

Signed-off-by: Krzysztof Wojcik <krzysztof.wojcik@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>