usb:hsotg:samsung: Remove the S3C_ prefix from registers definition.

This code removes the S3C_ prefix from s3c-hsotg driver. This change
provides more architecture independent code.

Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>