LU-5996 tests: check spaces and tabs in .sh files

This patch fixes checkpatch.pl script to check the following
coding style rules in .sh files:
- code indent should use tabs where possible
- no space before tabs
- no spaces at the start of a line

Signed-off-by: Jian Yu <jian.yu@intel.com>
Change-Id: I71821d2d15ca218528fcd8fb37119d0e0798027a
Reviewed-on: http://review.whamcloud.com/12976
Tested-by: Jenkins
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>