evaluate: permit get element on maps

evaluate: permit get element on maps

Its possible to add an element to a map, but you can't read it back:

before:
nft add element inet filter test "{ 18.51.100.17 . ad:c1:ac:c0:ce:c0 . 3761 : 0x42 }"
nft get element inet filter test "{ 18.51.100.17 . ad:c1:ac:c0:ce:c0 . 3761 : 0x42 }"
Error: No such file or directory; did you mean map ‘test’ in table inet ‘filter’?
get element inet filter test { 18.51.100.17 . ad:c1:ac:c0:ce:c0 . 3761 : 0x42 }
                        ^^^^
after:
nft get element inet filter test "{ 18.51.100.17 . ad:c1:ac:c0:ce:c0 . 3761 : 0x42 }"
table inet filter {
        map test {
                type ipv4_addr . ether_addr . inet_service : mark
                flags interval,timeout
                elements = { 18.51.100.17 . ad:c1:ac:c0:ce:c0 . 3761 : 0x00000042 }
        }
}

Signed-off-by: Florian Westphal <fw@strlen.de>