block: test-iosched: expose APIs to allow compiling ufs_test as a module

The UFS tests are used for testing the functionality and performance
of the UFS driver. Some of the tests call compare_buffer_to_pattern
for data integrity checking. This function should be exposed in order
to allow compilation of ufs_test as a module.

Change-Id: I2279b0ae9dbdf4ecad073fab2b15116be2ea1713
Signed-off-by: Gilad Broner <gbroner@codeaurora.org>
Signed-off-by: Maya Erez <merez@codeaurora.org>