drivers: phy: phy-samsung-usb2.c: Add missing MODULE_DEVICE_TABLE

Allow phy-exynos-usb2 to be autoloaded based on devicetree information.
Tested on Odroid X2 with its USB subsystem build as modules.

Signed-off-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>