iio: imu: mpu6050: Fix name/chip_id when using ACPI

When using ACPI, id is NULL and the current code automatically
defaults name to NULL and chip id to 0. We should instead use
the data provided in the ACPI device table.

Fixes: c816d9e7 ("iio: imu: mpu6050: fix possible NULL dereferences")
Signed-off-by: Daniel Baluta <daniel.baluta@intel.com>
Reviewed-By: Matt Ranostay <matt.ranostay@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>