ARM: dts: Update DWC3 usb controller to use new phy driver for exynos5250

Removing the dt node for older usb3 phy driver from Exynos5250
device tree and updating the dt node for DWC3 controller to
use new phy driver based on generic phy framework.

Signed-off-by: Vivek Gautam <gautam.vivek@samsung.com>
Reviewed-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>