ip/ipnexthop: fix unsigned overflow in parse_nh_group_type_res()

ip/ipnexthop: fix unsigned overflow in parse_nh_group_type_res()

0UL has type 'unsigned long' which is likely to be 64bit on modern machines. At
the same time, the '{idle,unbalanced}_timer' variables are declared as u32, so
these variables cannot be greater than '~0UL / 100' when 'unsigned long' is 64
bits. In such condition it is still possible to pass the check but get the
overflow later when the timers are multiplied by 100 in 'addattr32'.

Fix the possible overflow by changing '~0UL' to 'UINT32_MAX'.

Fixes: 91676718228b ("nexthop: Add support for resilient nexthop groups")
Signed-off-by: Maxim Petrov <mmrmaximuzz@gmail.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>