datatype: time_print() ignores -T

datatype: time_print() ignores -T

Honor NFT_CTX_OUTPUT_NUMERIC_TIME.

 # nft list ruleset
 table ip x {
        set y {
                type ipv4_addr
                flags timeout
                elements = { 1.1.1.1 timeout 5m expires 1m49s40ms }
        }
 }
 # sudo nft -T list ruleset
 table ip x {
        set y {
                type ipv4_addr
                flags timeout
                elements = { 1.1.1.1 timeout 300s expires 108s }
        }
 }

Closes: https://bugzilla.netfilter.org/show_bug.cgi?id=1561
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>