dtc: Sync with upstream version e9a77451cdd8

[jrtc27]

Summary

1c231509cf88 ("Validate integers fit in cells") is the only change
missing from our copy.

Test Plan

Ask manu nicely to make sure there aren't any bogus device trees this breaks :)
GNU dtc has this check (and with proper signedness checks, not my conservative
approximation) so all the vendored Linux ones should be fine, it's just our own
that could be an issue.

[imp]

Assuming this doesn't break building the dts we have in the tree.

[manu]

Don't think that it will break the custom DTS that we have so go ahead.
Thanks.