HID: hid-core: Fix incorrect function name in header

Fixes the following W=1 kernel build warning(s):

 drivers/hid/hid-core.c:2142: warning: expecting prototype for store_new_id(). Prototype was for new_id_store() instead

Cc: Jiri Kosina <jikos@kernel.org>
Cc: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Cc: Vojtech Pavlik <vojtech@suse.cz>
Cc: Michael Haboustak <mike-@cinci.rr.com>
Cc: linux-input@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>