net: openvswitch: Use ERR_CAST() to return

Using ERR_CAST() is more reasonable and safer, When it is necessary
to convert the type of an error pointer and return it.

Signed-off-by: Yan Zhen <yanzhen@vivo.com>
Acked-by: Eelco Chaudron <echaudro@redhat.com>
Reviewed-by: Aaron Conole <aconole@redhat.com>
Link: https://patch.msgid.link/20240829095509.3151987-1-yanzhen@vivo.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>