wifi: mt76: mt7915: mcu: lower default timeout

The default timeout set in mt76_connac2_mcu_fill_message of 20 seconds
leads to excessive stalling in case messages are lost.

Testing showed that a smaller timeout of 5 seconds is sufficient in
normal operation.

Signed-off-by: David Bauer <mail@david-bauer.net>
Link: https://patch.msgid.link/20250402004528.1036715-1-mail@david-bauer.net


Signed-off-by: Felix Fietkau <nbd@nbd.name>