HID: nintendo: Remove unused function

The function are defined in the hid-nintendo.c file, but not called
elsewhere, so delete the unused function.

drivers/hid/hid-nintendo.c:697:20: warning: unused function 'joycon_device_has_usb'.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=8704


Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>