network/services/ead: fix t_fromhex whitespace and non-hex parsing

[ManupaKDU]

Update t_fromhex to correctly ignore whitespace and non-hex digits during conversion, fulfilling the FIXME comment.

The parser counts valid hex characters using isxdigit from <ctype.h> to compute the size accurately. When extracting values, it consumes input by bypassing any invalid characters.

Signed-off-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

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PR created automatically by Jules for task 11444315272486179334 started by @manupawickramasinghe

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