ANDROID: usb: gadget: fix cannot create multiple android instances

Cannot use android_device to get multiple android instances.
The cdev will not be freed by the set_gadget_data(gadget, NULL),
so we can do not use the spinlock of gadget item to prevent
the condition.

Bug: 298603473
Fixes: dd139186 ("ANDROID: usb: gadget: fix NULL pointer dereference in android_setup")
Signed-off-by: William Wu <william.wu@rock-chips.com>
Signed-off-by: Bin Yang <yangbin@rock-chips.com>
Change-Id: Ic0c72971051401d218e2eba75c40194933290e16