PC Engines APU Flash WP GPIO control added to flash command

[matmacieje]

Partially addressed here on OSFV side, but we definitely need more consistent solution on osfv-scripts side.

• WP GPIO must be set to low for Flash access
• WP GPIO must be set to high-z to continue serial port operation
• Affects mostly APU 3 & 6 but observed also on APU 4

OSFV side fixes:
Dasharo/open-source-firmware-validation#1158

[SergiiDmytruk]

While causing an issue for OSFV, from the point of view of this project this looks like a feature rather than a bug. Aligned label with the issue type.

[miczyg1]

WP GPIO must be set to low for Flash access

Not the other way around? Shorting the WP pin to GND will cause the protection to be active.

WP GPIO must be set to high-z to continue serial port operation

Not sure how inactive flash protection would cause issues with serial port. Are we sure the connection is correct in lab?

[matmacieje]

@miczyg1 connections were verified by @JakubSobota plus he discovered influence of the GPIO on serial port.
Jira ticket: UCYY-304

I implemented it this way in OSFV and it fixed both flash chip detection and serial port issues.