usb: gadget: s3c-hsotg: Allow driver instantiation using device tree

This patch adds OF match table to the driver to allow instantiating it
using device tree.

Signed-off-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>