usb: ehci-exynos: Use struct device instead of platform_device

Change to use struct device instead of struct platform_device
for some static functions.

Signed-off-by: Vivek Gautam <gautam.vivek@samsung.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Jingoo Han <jg1.han@samsung.com>
Acked-by: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>