anv: convert C generation to template in anv_entrypoints_gen.py

anv: convert C generation to template in anv_entrypoints_gen.py

This produces a file that is identical except for whitespace, there is a
table that has 8 columns in the original and is easy to do with prints,
but is ugly using mako, so it doesn't have columns; the data is not
inherently tabular.

Signed-off-by: Dylan Baker <dylanx.c.baker@intel.com>