spectrum: acl_tcam: Fix catchall prio value

This fixes an issue reported by smatch:
mlxsw_sp_acl_tcam_chunk_create() warn: impossible condition '(priority == (-1)) => (0-u32max == u64max)'

Reported-by: Or Gerlitz <ogerlitz@mellanox.com>
Reported-by: Ido Schimmel <idosch@mellanox.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: 22a67766 ("mlxsw: spectrum: Introduce ACL core with simple TCAM implementation")
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>