test: Remove not needed null check

test: Remove not needed null check

In ut_report() there is a null check for stats but stats was already
dereferenced on the line before and is again dereferenced later in the
same function. Also the two places where ut_report() is called from will
have initialised the parameter so there is no chance that stats will be
null. So to prevent static analysis complaining of a use before check
just remove the check.

This issue was found by Smatch.

Signed-off-by: Andrew Goodbody <andrew.goodbody@linaro.org>