Change in coreboot[master]: device: Prevent using `mmconf_resource` with invalid values

[Nico Huber (Code Review)]

Attention is currently required from: Tim Wawrzynczak, Angel Pons, Arthur Heymans, Evgeny Zinoviev, Kyösti Mälkki, Patrick Rudolph, Felix Held.
Nico Huber has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/49744 )

Change subject: device: Prevent using `mmconf_resource` with invalid values
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Patch Set 2:

(1 comment)

File src/device/device_util.c:

https://review.coreboot.org/c/coreboot/+/49744/comment/c66a16ad_0b959631 
PS2, Line 881: CONFIG_MMCONF_BASE_ADDRESS <= 0
> You can still attempt to call mmconf_resource() with !MMCONF_SUPPORT, so this check isn't redundant. […]

Shouldn't it be

if (!CONFIG(MMCONF_SUPPORT))
            dead_code();

then?