Move per-chip testmode data to mt7915_phy, to properly support
reg_backup and rx status of each band in testmode.
Signed-off-by: Shayne Chen <shayne.chen@mediatek.com>
Acked-by: Ryder Lee <ryder.lee@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>