mfd: core: Fix ACPI child matching by _HID/_CID

If MDF child devices have separate ACPI nodes identified
by _HID/_CID, they will not be assigned the intended
ACPI companion.

acpi_match_device_ids will return 0 if a the child device
matches the _HID/_CID, so this patch changes the matching
condition to check for 0 on success.

Signed-off-by: Irina Tirdea <irina.tirdea@intel.com>
Acked-by: Mika Westerberg <mika.westeberg@linux.intel.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>