[M] Change in coreboot[main]: commonlib/device_tree.c: Add read reg property helper

[Julius Werner (Code Review)]

Attention is currently required from: Arthur Heymans, Maximilian Brune.

Julius Werner has posted comments on this change by Maximilian Brune. ( https://review.coreboot.org/c/coreboot/+/83457?usp=email )

Change subject: commonlib/device_tree.c: Add read reg property helper
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Patch Set 3:

(1 comment)

File src/commonlib/device_tree.c:

https://review.coreboot.org/c/coreboot/+/83457/comment/d1b15d5b_f928bd5d?usp... :
PS3, Line 1013: 	size_t count = prop->prop.size / (4 * addr_cells + 4 * size_cells);
Can we factor out everything starting here into a common function that's used by both (dt and fdt)?