usb: s3c-otg: Rename struct s3c_plat_otg_data

The driver is actually for the Designware DWC2 controller.
This patch is the first to rename global symbol, the struct
s3c_plat_otg_data.

The rename is done automatically:
	$ sed -i "s/s3c_plat_otg_data/dwc2_plat_otg_data/g" \
		`git grep s3c_plat_otg_data | cut -d : -f 1`

Signed-off-by: Marek Vasut <marex@denx.de>