Squashed 'external/devlib/' changes from 17d4b22b9f0c..e01a76ef1bf5

e01a76ef1bf5 doc: Explain the 'tar' flag of target.read_tree_values
9fcca2503127 hwmon: Robustify hwmon scan
a6b9542f0f8c target: Speed-up read_tree_values()
413e83f5d632 target/kernelconfig: Add alias for itteritems
ac1987342328 target/TypedKernelConfig: Fix converting to string method

git-subtree-dir: external/devlib
git-subtree-split: e01a76ef1bf5a9f221136198f27233d2308a320b