net: bcmasp: Fix error code in probe()

Return an error code if bcmasp_interface_create() fails.  Don't return
success.

Fixes: 490cb412

 ("net: bcmasp: Add support for ASP2.0 Ethernet controller")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Michal Kubiak <michal.kubiak@intel.com>
Reviewed-by: Justin Chen <justin.chen@broadcom.com>
Link: https://patch.msgid.link/ZoWKBkHH9D1fqV4r@stanley.mountain
Signed-off-by: Jakub Kicinski <kuba@kernel.org>