mesh: Use appropriate BLOCKED state duration

mesh: Use appropriate BLOCKED state duration

Previously, BLOCKED state duration slightly increased up to 3600. Though
the BLOCKED state could be canceled by ap_handle_timer(). Because the
timer timeouts in ap_max_inactivity(default=300sec) and remove STA
objects (the object retains BLOCKED state).

This patch re-designs my commit bf51f4f82bdb50356de5501acac53fe1b91a7b86
('mesh: Fix remaining BLOCKED state after SAE auth failure') to replace
mesh_auth_block_duration by ap_max_inactivity and remove incremental
duration.

Signed-off-by: Masashi Honma <masashi.honma@gmail.com>