ARM: exynos5420: Leave VBUS GPIO configuration up to common code

ARM: exynos5420: Leave VBUS GPIO configuration up to common code

Since commit 4a271cb1b4ffdf330 (exynos: usb: Switch USB VBUS GPIOs to be
device tree configured) it's not needed for the board specific files to
turn on the VBUS GPIO by hand as that gets done based on device tree. So
drop the redundant code from the SMDK5420 board file.

Signed-off-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>
Acked-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>