misc: eeprom: at24: Tell the compiler that ACPI functions may not be used

... as is the case when !CONFIG_ACPI.

Fixes the following W=1 kernel build warning:

 drivers/misc/eeprom/at24.c:228:36: warning: ‘at24_acpi_ids’ defined but not used [-Wunused-const-variable=]

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Acked-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Link: https://lore.kernel.org/r/20200701093616.GX1179328@dell


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>