Specify location of CMake tests

The create_cmake.prf file now checks for the existence of tests, so
ensure that they are searched for in the correct path.

Change-Id: Ibac09b01e1d2546b5ee553990e6257fd92d453bf
Reviewed-by: Andrew Knight <andrew.knight@digia.com>
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@digia.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>