mt76: mt76x02: fix beacon timer issue

When mt76x0 and mt76x2 beacon code was unified, it changed the order in which
beacon enable and beacon interval are configured.
Configuring beacon enable before beacon interval can in some cases cause
problems with the beacon timer, leading to clients not waking up properly
from powersave mode.
Fix this by changing the order back to interval first, then enable.

Fixes: cc726268 ("mt76: move mt76x02_bss_info_changed in mt76x02-lib module")
Cc: stable@vger.kernel.org
Signed-off-by: Felix Fietkau <nbd@nbd.name>