selftests: sync: add config fragment for testing sync framework

Unless the software synchronization objects (CONFIG_SW_SYNC) is enabled,
the sync test will be skipped:

TAP version 13
1..0 # Skipped: Sync framework not supported by kernel

Add a config fragment file to be able to run "make kselftest-merge" to
enable relevant configuration required in order to run the sync test.

Signed-off-by: Fathi Boudra <fathi.boudra@linaro.org>
Link: https://lkml.org/lkml/2017/5/5/14


Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>