usb: dwc2: gadget: add reset flag in init function

Add a flag to request physical reset of the controller when
s3c_hsotg_core_init_disconnected is called.
During the usb reset, controller must not be fully reconfigured and
resetted. Else this leads to shorter chirp-k duration during
enumeration.

Tested-by: Robert Baldyga <r.baldyga@samsung.com>
Acked-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Gregory Herrero <gregory.herrero@intel.com>
Signed-off-by: Mian Yousaf Kaukab <yousaf.kaukab@intel.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>