ARM: exynos_defconfig: Enable locking test options

exynos_defconfig, beside serving as a reference config for Exynos-based
devices, is used by developers during regular development work.
Enabling options responsible for locking tests allows to discover bugs
in drivers and mach code earlier.

This enables:
1. Detection of sleeping in atomic sections (DEBUG_ATOMIC_SLEEP),
2. Full lockdep (DEBUG_LOCK_ALLOC and PROVE_LOCKING which makes other
   lock debug entries unneeded),
3. Detection of soft, kernel lockups (SOFTLOCKUP_DETECTOR).

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: Anand Moon <linux.amoon@gmail.com>