mt76: mt7915: use mt7915_mcu_get_mib_info() to get survey data

Firmware functions (SCS, MU ...) also require read-clear phy counters,
hence firmware prepares a global task to read shared fields out to a
shared pool to avoid concurrency. Switch to event format accordingly.

Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>