[L] Change in coreboot[main]: mb/asrock: Add Z77 Extreme4

[Keith Hui (Code Review)]

Attention is currently required from: Angel Pons, Nicholas Chin, Riku Viitanen.

Keith Hui has posted comments on this change by Riku Viitanen. ( https://review.coreboot.org/c/coreboot/+/85772?usp=email )

Change subject: mb/asrock: Add Z77 Extreme4
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Patch Set 18:

(2 comments)

File src/mainboard/asrock/z77_extreme4/devicetree.cb:

https://review.coreboot.org/c/coreboot/+/85772/comment/fe0efee5_911f9cc2?usp... :
PS18, Line 46: xhci_overcurrent_mapping
Gone after CB:85922.

File src/mainboard/asrock/z77_extreme4/early_init.c:

https://review.coreboot.org/c/coreboot/+/85772/comment/0aa39fef_bbc22f83?usp... :
PS18, Line 10: CONSOLE_SERIAL
Check if nuvoton_enable_serial() already has this condition.