net: lwm2m: remove IP CONFIG checks in lwm2m_parse_peerinfo()

CONFIG_NET_IPV* checks are not needed in lwm2m_parse_peerinfo().
The functions used are always available.  Worse, having these checks
forces the need to enable CONFIG_NET_IPV4 or IPV6 when it's not really
needed (LwM2M could be using an offloaded IP stack).

Fixes: https://github.com/zephyrproject-rtos/zephyr/issues/17401



Signed-off-by: Michael Scott <mike@foundries.io>