scsi: ufs: add data integrity test to ufs unit tests

This testcase checks data integrity in a random I/O usecase.
The test writes QUEUE_MAX_REQUESTS (usually 118) requests of size 4KB
to randomly and uniquely chosen LBAs. A different pattern is written
to each LBA (pattern written is index of LBA). After successfully writing,
the test reads from the above LBAs and verifies the pattern.

Change-Id: I09c6dda12834f06ae393411501f443bfd058dea4
Signed-off-by: Lee Susman <lsusman@codeaurora.org>