lwtunnel: ignore any TUNNEL_OPTIONS_PRESENT flags set by users

TUNNEL_OPTIONS_PRESENT (TUNNEL_GENEVE_OPT|TUNNEL_VXLAN_OPT|
TUNNEL_ERSPAN_OPT) flags should be set only according to
tb[LWTUNNEL_IP_OPTS], which is done in ip_tun_parse_opts().

When setting info key.tun_flags, the TUNNEL_OPTIONS_PRESENT
bits in tb[LWTUNNEL_IP(6)_FLAGS] passed from users should
be ignored.

While at it, replace all (TUNNEL_GENEVE_OPT|TUNNEL_VXLAN_OPT|
TUNNEL_ERSPAN_OPT) with 'TUNNEL_OPTIONS_PRESENT'.

Fixes: 3093fbe7 ("route: Per route IP tunnel metadata via lightweight tunnel")
Fixes: 32a2b002

 ("ipv6: route: per route IP tunnel metadata via lightweight tunnel")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>