ARM: dts: exynos: Fix DTC unit name warnings in Exynos5440

Fix following DTC warnings in Exynos5440 boards:

Warning (unit_address_vs_reg): Node /pinctrl has a reg or ranges property, but no unit name
Warning (unit_address_vs_reg): Node /rtc has a reg or ranges property, but no unit name

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>