3B+ revision a020d4 is missing.

[stephan57160]

Just received a few 3B+ with some unknown revision:

$> grep -e Model -e Revision /proc/cpuinfo
Revision	: a020d4
Model		: Raspberry Pi 3 Model B Plus Rev 1.4
$> 

Still digging in documentation, but I can't find this one under:
https://github.com/raspberrypi/documentation/blob/develop/documentation/asciidoc/computers/raspberry-pi/revision-codes.adoc

[aallan]

Ping @JamesH65 who probably is the best person for this one?

[JamesH65]

That's just the v1.4 board (New PMIC), see PCN here https://pip.raspberrypi.com/categories/797-pcn/documents/RP-003337-PC/Pi3B-Revision-9-PCN.pdf. I'll update the page when I get the chance. Note that the table in the docs is not guaranteed to cover everything, and should not be relied upon for board identification - use the scheme noted later on the page.

[JamesH65]

See #3354