usb:hsotg:samsung: Remove platform dependent functions from s3c-hsotg

Two functions - namely: s3c_hsotg_gate and s3c_hsotg_otgreset are platform
dependent and therefore removed from Samsung's generic s3c-hsotg 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>