ARM: exynos_defconfig: Bring back explicitly wanted options

Few options KALLSYMS_ALL, SCSI, PM_DEVFREQ and mutex/spinlock debugging
were removed with savedefconfig because they were selected by other
options.  However these are user-visible options and they might not be
selected in the future.  Exactly this happened with commit 0e4a459f
("tracing: Remove unnecessary DEBUG_FS dependency") removing the
dependency between DEBUG_FS and TRACING.

To avoid losing these options in the future, explicitly mention them in
defconfig.

Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>