LU-7472 tests: Allows to specify IOR block size with suffix

LU-7472 tests: Allows to specify IOR block size with suffix

Added a variable io_blockUnit which can
be set to K, M or G and adjust the IOR block sizes.
Modified to keep m as the default option. Default block
size for IOR tests would be 6MB.

Test-Parameters: trivial
Seagate-bug-id: MRP-2685
Change-Id: Ie7a11d8cb06faad902abc56bca4fc5914df8f42d
Signed-off-by: Aditya Pandit <aditya.pandit@seagate.com>
Signed-off-by: Ashish Purkar <ashish.purkar@seagate.com>
Reviewed-on: http://review.whamcloud.com/17354
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: James Nunez <james.a.nunez@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>