config: drop double size lease times; they are all UINT32_MAX;

config: drop double size lease times; they are all UINT32_MAX;

This now prevents implicit 64 bit->32 bit truncation which may flag
compiler errors later on down the road.

All of the variables receiving from parse_leasetime() are uint32_t
anyway, so max 136 years of valid lease time will have to suffice :)

Signed-off-by: Paul Donald <newtwen+github@gmail.com>
Link: https://github.com/openwrt/odhcpd/pull/225
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>