usb: gadget: s3c-hsotg: fix clear feature ENDPOINT_HALT

All requests for endpoint are completed when it was halted and the halt was
cleared by CLEAR_FEATURE, but not when new state is same as previous.

Signed-off-by: Robert Baldyga <r.baldyga@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>