Reviewed-by: Hannes Reinecke <hare@suse.com>

Restore compatibility with scsi_id by truncating ID_WWN to 16 chars.
ID_WWN_WITH_EXTENSION is what actually matters for SCSI, but we
should get this right nevertheless.

Separate the "compat" rules for creating ID_* variables from
SCSI_* variables from the block doing actual inquiry.

Also improve code readability by spelling out the sysfs vs. sg
code more clearly. This patch should have no functional impact.

In order to replace scsi_id functionality from udev's
60-persistent-storage.rules, add code for non-SCSI devices that support sg
INQUIRY (only CCISS at this time). CCISS has been deprecated since Linux 4.14,
but these rules are supposed to work with older kernels, too.

In order to replace scsi_id functionality in udev's
60-persistent-storage.rules, add support for some non-block devices.

These rules have been tested using the emulated virtual tape library
mhVTL (https://github.com/markh794/mhvtl). It turns out that preferring
sysfs attributes for inquiry is even more beneficial for those than
for disks.

ata_id or usb_id may have already set these variables.
Don't overwrite them in this case.

scsi_id sets ID_TARGET_PORT=%x.

As of 2018 kernel 4.15, the kernel doesn't provide VPD pages for "SPC" devices
(SCSI version 0x03, ANSI INCITS 301-1997) in sysfs. It's usually safe to try
though (no counter-example is known), and for scsi_id compatibility, we have
to try. If the kernel ever changes its policy, this rule can perhaps be dropped.