ARM: s3c6400_defconfig: Bring back lost (but wanted) options

The config was not updated for some time so it needs updates to get the
same options as wanted initially:
 - SYSFS_DEPRECATED is now needed for SYSFS_DEPRECATED_V2;
 - PWM is now needed for BACKLIGHT_PWM;
 - DEBUG_SPINLOCK_SLEEP was replaced by DEBUG_ATOMIC_SLEEP;

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>