T-API: optimization of cv::warpAffine (INTER_CUBIC & INTER_LINEAR)

**Description:**
* eliminated temporary arrays in kernel
* since the interpolation is done with reduced accuracy, I made constant buffer with precomputed coefficients
* changed work type from int to float for uchar, char, short, ushort, int 

**Performance report:**
http://ocl.itseez.com/intel/export/perf/pr/2869/report/

check_regression=*OCL*WarpAffine*
test_filter=*OCL*WarpAffine*
test_modules=imgproc
build_examples=OFF