hw/net/rocker/rocker_of_dpa.c: Remove superfluous error check

hw/net/rocker/rocker_of_dpa.c: Remove superfluous error check

of_dpa_cmd_add_acl_ip() is called from a single place, and despite the
fact that it always returns ROCKER_OK, its return value is still checked
by the caller.

Change of_dpa_cmd_add_acl_ip() to return void and remove the superfluous
check from of_dpa_cmd_add_acl().

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2471
Signed-off-by: Rodrigo Dias Correa <r@drigo.nl>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Message-id: 20241114075051.404284-1-r@drigo.nl
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>