doc: replace asym crypto code with literal includes

doc: replace asym crypto code with literal includes

The programmer's guide for cryptodev included sample code for using
Asymmetric crypto. This is now replaced with direct code from the test
application, using literal includes. It is broken into snippets as the
test application didn't have all of the required code in one function.

Signed-off-by: Ciara Power <ciara.power@intel.com>
Acked-by: Anoob Joseph <anoobj@marvell.com>
Acked-by: Fan Zhang <roy.fan.zhang@intel.com>
Acked-by: Akhil Goyal <gakhil@marvell.com>