power: supply: bq24257: skip 'struct acpi_device_id' when !CONFIG_ACPI

Since ACPI_PTR() is used to NULLify the value when !CONFIG_ACPI, the
struct acpi_device_id becomes unused:

  drivers/power/supply/bq24257_charger.c:1155:36: warning:
    'bq24257_acpi_match' defined but not used [-Wunused-const-variable=]

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>