net: microchip: sparx5: kunit test: Fix compile warnings.

When VCAP_KUNIT_TEST is enabled the following warnings are generated:

drivers/net/ethernet/microchip/vcap/vcap_api_kunit.c:257:34: warning: Using plain integer as NULL pointer
drivers/net/ethernet/microchip/vcap/vcap_api_kunit.c:258:41: warning: Using plain integer as NULL pointer
drivers/net/ethernet/microchip/vcap/vcap_api_kunit.c:342:23: warning: Using plain integer as NULL pointer
drivers/net/ethernet/microchip/vcap/vcap_api_kunit.c:359:23: warning: Using plain integer as NULL pointer
drivers/net/ethernet/microchip/vcap/vcap_api_kunit.c:1327:34: warning: Using plain integer as NULL pointer
drivers/net/ethernet/microchip/vcap/vcap_api_kunit.c:1328:41: warning: Using plain integer as NULL pointer

Therefore fix this.

Fixes: dccc30cc ("net: microchip: sparx5: Add KUNIT test of counters and sorted rules")
Fixes: c956b9b3 ("net: microchip: sparx5: Adding KUNIT tests of key/action values in VCAP API")
Fixes: 67d63751

 ("net: microchip: sparx5: Adding KUNIT test for the VCAP API")
Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>