libfdt: Clean up error codes

First, this patch removes several underused error codes:
FDT_ERR_BADPOINTER and FDT_ERR_BADHEADER were not used at all and are
simply removed.  FDT_ERR_SIZE_MISMATCH was very similar in spirit to
FDT_ERR_NOSPACE, and used only in circumstances where there can be no
confusion between the two, so is removed and folded into
FDT_ERR_NOSPACE.  FDT_ERR_INTERAL was used on only one place, on a
"can't happen" check.  It seems of little value so the check and error
code are removed also.

Second, the error codes have been re-numbered and grouped roughly by
severity.  That is codes which can reasonably occur in normal
operation separated from those which indicate bad parameters (and
therefore a bug in the caller) or a bad or corrupted device tree blob.

Third the test function fdt_strerror() is cleaned up a little based on
these changes.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
4 files changed