net: microchip: vcap: Merge the vcap_ag_api_kunit.h into vcap_ag_api.h

Currently there are 2 files that contain the keyfields, keys,
actionfields and actions. First file is used by the kunit while the
second one is used by VCAP api.
The header file that is used by kunit is just a super set of the of the
header file used by VCAP api.
Therefore not to have duplicate information in different files which is
also harder to maintain, create a single file that is used both by API
and by kunit.

Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>