tests: Rework the convolve_test

Besides just general cleanup, the major changes are :
 - Always run the reference / base implementation and print
   those results. Theses should be consistent across platform
   and check the base implementation works
 - Run the optimized version and compare results with small
   error tolerance against the reference results.

Change-Id: I4e203d2c4b778af77d630ed15d4cef6b0c0eb76d
Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
2 files changed