tc: m_connmark: fix action error messages

tc: m_connmark: fix action error messages

action m_connmark returns error messages identifying itself as the
'simple' action instead of 'connmark' action. e.g.

tc filter add dev eth0 protocol all u32 match u32 0 0 flowid 1:1 \
	action connmark index wrong
simple: Illegal "index"
bad action parsing
parse_action: bad value (3:connmark)!
Illegal "action"

In what is most likely a copy/paste error from the simple action example
code, fix connmark error messages to identify themselves as coming from
connmark.

tc filter add dev eth0 protocol all u32 match u32 0 0 flowid 1:1 \
	action connmark index wrong
connmark: Illegal "index"
bad action parsing
parse_action: bad value (3:connmark)!
Illegal "action"

While we're here also fixup the 'Illegal "Zone"' error code to say
'Illegal "zone"' instead of 'Illegal "index"'

Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>