HID: nintendo: Remove some unused functions

These functions are defined in the hid-nintendo.c file, but not
called elsewhere, so delete these unused functions.

drivers/hid/hid-nintendo.c:672:20: warning: unused function 'joycon_device_is_procon'.
drivers/hid/hid-nintendo.c:682:20: warning: unused function 'joycon_device_is_snescon'.
drivers/hid/hid-nintendo.c:687:20: warning: unused function 'joycon_device_is_gencon'.
drivers/hid/hid-nintendo.c:692:20: warning: unused function 'joycon_device_is_n64con'.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=9265


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