RFC: initial check for fdt and its containing buffer

[fozog]

It is not inherently an error to have a containing buffer larger than the actual FDT. FDTs can be grown and hence a larger buffer may just accomodate expected growths.

However, a buffer that is actually smaller than the value in the FDT header does not represent a valid situation and it is better to bail off early.

[coveralls]

Pull Request Test Coverage Report for Build 3912025538

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

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Details

• 0 of 1 (0.0%) changed or added relevant line in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 59.657%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/base/tree.rs	0	1	0.0%

Totals
Change from base Build 3905624911:	0.0%
Covered Lines:	556
Relevant Lines:	932

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💛 - Coveralls