tinycrypt/sha256: Array compared to NULL has no effect

This commit fixes the issue reported by Coverity: an array compared
against NULL is always false.

Coverity-CID: 143715
Coverity-CID: 143730

Change-Id: Ie3c87f892c2b2a337981125e2a92c37c579d4b38
Signed-off-by: Flavio Santes <flavio.santes@intel.com>
1 file changed