ARM: dts: disable 'always on' for BUCK8 regulator for exynos4412-odroid-common

On Odroid U2/U3 BUCK8 is used for providing power to also to P3V3
source, which is also connected to LAN9730 chip's nRESET signal. To
reset lan chip on system reboot, the BUCK8 output should not be used in
'always on' mode. This change has no impact on X/X2 boards.

Signed-off-by: Kamil Debski <k.debski@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>