LU-11803 tests: don't assume obd device name

LU-11803 tests: don't assume obd device name

Several tests created to exercise lustre were developed on the
x86 platform and it was assumed the device name exposed in the
sysfs tree are the same across all platforms. Additionally
we can update the test to handle the case of using an uuid
format for the sysfs directory naming instead of an internal
address pointer.

Lustre-change: https://review.whamcloud.com/33894
Lustre-commit: b8e6c8bdca9bd0e12d78cd4a06800c13f4293325

Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Change-Id: I704d13059f76337fa49aab77f3e748a70a74f1bc
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: James Nunez <jnunez@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/34783
Tested-by: Jenkins
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>