Re: dtc: Check return value from fwrite()

There's one place in flattree.c where we currently ignore the return
value from fwrite().  On some gcc/glibc versions, where fwrite() is
declared with attribute warn_unused_result, this causes a warning.

This patch fixes the warning, by checking the fwrite() result.

Signed-off-by: David Gibson <redacted>

Applied.

Thanks,
jdl