net: ipv6: net.ipv6.variable_buf_size reports usage fault

[katgiadla]

Describe the bug
Test tests/net/ipv6/net.ipv6.variable_buf_size reports timeout.

Observed for nrf5340dk/nrf5340/cpuapp.

To Reproduce
Steps to reproduce the behavior:

1. have nrf5340dk/nrf5340/cpuapp connected
2. go to your zephyr dir
3. call ./scripts/twister -s net.ipv6.variable_buf_size -p nrf5340dk/nrf5340/cpuapp --device-testing --device-serial /dev/ttyACM1 -v --inline-logs --west-flash="--erase"
4. See console output with error

Expected behavior
Valid console output

Impact
Not clear

Logs and console output

*** Booting Zephyr OS build v4.0.0-3862-g76e1e1b80470 ***
Running TESTSUITE net_ipv6
===================================================================
START - test_address_lifetime
 PASS - test_address_lifetime in 0.202 seconds
===================================================================
START - test_change_ll_addr
 PASS - test_change_ll_addr in 0.002 seconds
===================================================================
START - test_cmp_prefix
 PASS - test_cmp_prefix in 0.001 seconds
===================================================================
START - test_dad_conflict
E: ICMPv6 handling failure (-5)
 PASS - test_dad_conflict in 0.102 seconds
===================================================================
START - test_dad_on_ll_addr_after_carrier_toggle
 PASS - test_dad_on_ll_addr_after_carrier_toggle in 0.013 seconds
===================================================================
START - test_dad_on_ll_addr_after_iface_up
E: ***** USAGE FAULT *****
E:   Stack overflow (context area not valid)
E: r0/a1:  0x75ddffbf  r1/a2:  0xd0429d55  r2/a3:  0x00014f0a
E: r3/a4:  0x01000000 r12/ip:  0x20000758 r14/lr:  0x0000000d
E:  xpsr:  0x00000000
E: Faulting instruction address (r15/pc): 0x20002f48
E: >>> ZEPHYR FATAL ERROR 2: Stack overflow on CPU 0
E: Current thread: 0x20000a10 (test_dad_on_ll_addr_after_iface)
E: Halting system

Environment (please complete the following information):

• OS: Ubuntu 20.04.1 LTS
• Toolchain: Zephyr SDK 0.17.0
• Commit SHA or Version used: v4.0.0-3862-g76e1e1b80470

Additional information
Probably introduced by 2f10d7d