Allow probe_disks to ignore disks that cannot be read from

[CAReyes]

Do not hard error when probe_disks() tries to read one of the disks on a device cannot be read. Log the error instead and return the disks that can be read.

This allows certain model year MacBookPros to install Pop without deleting disks.

[CAReyes]

Could someone help setup a test build? I have not been able to test this yet.