wlcore: modify bss loss parameters

Modify default parameters to reduce firmware BSS lose
probability in congested environment.

[Applied to 18xx configuration as well - Arik]

Signed-off-by: Igal Chernobelsky <igalc@ti.com>
Signed-off-by: Arik Nemtsov <arik@wizery.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>