usb:hsotg:samsung: Use new udc_start and udc_stop callbacks

Replace of deprecated start and stop callbacks with a udc_start and
udc_stop ones.

Now the bind from composite driver is NOT called explicitly, so more
work needs to be done at s3c_udc_probe. Especially enabling SoC clocks
and power for runtime determination of EP number.
After probing, those sources are disabled and enabled again at udc_start
and pullup afterwards.

Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
Signed-off-by: Sangwook Lee <sangwook.lee@linaro.org>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>