ARM: dts: Correct typo in use of samsung,pin-drv for exynos5250

Corrects an obvious typo in the Arndale pinctrl descriptions in DT.
The samsung-pinctrl driver uses the correct name.

Signed-off-by: Al Stone <al.stone@linaro.org>
Reviewed-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>