net: Stackoverflow in net mgmt thread

[alexanderwachter]

Describe the bug
Stack overflow in net mgmt event thread. This bug was observed on a net_l2 layer that
is not yet submitted to zephyr (6LoCAN). Maybe it can't be reproduced with Ethernet.

To Reproduce

• Build net sockets echo client sample for nucleo_f746zg board
• Enable stack sentinal and thread names
• Flash board
• Open GDB start debugging and enter print (struct k_thread) <0x thread id from crash report>

Expected behavior
Sample should work without stack overflow.

Impact
Sample does not work due to stack overflow.

Screenshots or console output

***** Stack Check Fail! *****
Current thread ID = 0x200014c4
Faulting instruction address = 0x8015b2a

Environment (please complete the following information):

• OS: Linux
• Toolchain: native
• 1.14