w1: ds250x: Fix build error without CRC16

If CRC16 is not set, building will fails:

drivers/w1/slaves/w1_ds250x.o: In function `w1_ds2505_read_page':
w1_ds250x.c:(.text+0x82f): undefined reference to `crc16'
w1_ds250x.c:(.text+0x90a): undefined reference to `crc16'
w1_ds250x.c:(.text+0x91a): undefined reference to `crc16'

Reported-by: Hulk Robot <hulkci@huawei.com>
Fixes: 25ec8710

 ("w1: add DS2501, DS2502, DS2505 EPROM device driver")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20190920060318.35020-1-yuehaibing@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>