This reverts
commit 6a4290cc ("usb: dwc3: gadget: set the OTG flag in dwc3 gadget driver.")

We don't yet support any of the OTG mechanisms (HNP/SRP/ADP)
and are not setting gadget->otg_caps, so don't set gadget->is_otg
flag.

If we do then we end up publishing a OTG1.0 descriptor in
the gadget descriptor which causes device enumeration to fail
if we are connected to a host with CONFIG_USB_OTG enabled.

Host side log without this patch

[   96.720453] usb 1-1: new high-speed USB device number 2 using xhci-hcd
[   96.901391] usb 1-1: Dual-Role OTG device on non-HNP port
[   96.907552] usb 1-1: set a_alt_hnp_support failed: -32
[   97.060447] usb 1-1: new high-speed USB device number 3 using xhci-hcd
[   97.241378] usb 1-1: Dual-Role OTG device on non-HNP port
[   97.247536] usb 1-1: set a_alt_hnp_support failed: -32
[   97.253606] usb usb1-port1: attempt power cycle
[   97.960449] usb 1-1: new high-speed USB device number 4 using xhci-hcd
[   98.141383] usb 1-1: Dual-Role OTG device on non-HNP port
[   98.147540] usb 1-1: set a_alt_hnp_support failed: -32
[   98.300453] usb 1-1: new high-speed USB device number 5 using xhci-hcd
[   98.481391] usb 1-1: Dual-Role OTG device on non-HNP port
[   98.487545] usb 1-1: set a_alt_hnp_support failed: -32
[   98.493532] usb usb1-port1: unable to enumerate USB device
Signed-off-by: NRoger Quadros <rogerq@ti.com>
Signed-off-by: NFelipe Balbi <felipe.balbi@linux.intel.com>