fix compilation error about missing braces

IEC_TIMESPEC has two fields tv_sec and tv_nsec.

Compilation error:
./build/POUS.c:600:45: error: missing braces around initializer [-Werror=missing-braces]
static const STEP temp_step = {{0, 0}, 0, {0, 0}};
^
compilation terminated due to -Wfatal-errors.

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matiec (2009.0-%DATEVERSION%) unstable; urgency=low

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  * Initial release (Closes: #nnnn)  <nnnn is the bug number of your ITP>

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 -- edouard <edouard.tisserant@gmail.com>  Wed, 21 Nov 2007 17:01:50 +0100

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