Fixed some illegal implicitly type conversions between vector and scalar...

... data type.

According to ocl spec 6.2.1:
  Implicit conversions between built-in vector data types are disallowed.

We can't implicitly convert a scalar data to a vector data.
Issue reference: http://code.opencv.org/issues/3416

Signed-off-by: Zhigang Gong <zhigang.gong@intel.com>