wifi: mt76: mt7915: firmware restart on devices with a second pcie link

wifi: mt76: mt7915: firmware restart on devices with a second pcie link

It seems that the firmware checks the register used for detecting matching
PCIe links in order to figure out if a secondary PCIe link is enabled.
Write the register again just before starting the firmware on hw reset,
in order to fix an issue that left the second band unusable after restart.

Fixes: 9093cfff72e3 ("mt76: mt7915: add support for using a secondary PCIe link for gen1")
Link: https://patch.msgid.link/20241230194202.95065-11-nbd@nbd.name
Signed-off-by: Felix Fietkau <nbd@nbd.name>