config: fix memleak during odhcpd reload

config: fix memleak during odhcpd reload

- The memset in close_interface reset the pios pointer before it
  could be freed, causing a memory leak. Relocate the free call
  to clean_interface to ensure proper deallocation.

- Use realloc instead of malloc in config_load_ra_pio()
  This function may be called multiple times during odhcpd reload,
  and using malloc without freeing the previous allocation was
  causing memory leaks.

Signed-off-by: Fei Lv <[email protected]>
Link: https://github.com/openwrt/odhcpd/pull/309
Signed-off-by: Álvaro Fernández Rojas <[email protected]>