ACPI: scan: Fix an error message in DisCo for Imaging support

The recently merged DisCo for Imaging support used a wrong printk
specifier in printing a message. Fix it by using %zu instead of %lu.
Also use "bits" instead of "bytes" as these are indeed bytes.

Fixes: a6cb0a61

 ("ACPI: scan: Extract MIPI DisCo for Imaging data into swnodes")
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>