wifi: mt76: mt792x: add MT7927 WFSYS reset support

wifi: mt76: mt792x: add MT7927 WFSYS reset support

Add a dedicated MT7927 WFSYS reset path in mt792x_wfsys_reset().

Unlike the existing connac2/connac3 reset flow that toggles the WFSYS
software reset bit and waits for init-done, MT7927 reset is driven
through CBInfra and requires polling ROMCODE_INDEX until the MCU returns
to the idle value after reset.

Keep this dormant for now: no MT7927 PCI IDs are added by this patch, so
it only prepares the reset logic without making the driver bind to MT7927
hardware yet.

Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Link: https://patch.msgid.link/20260425195011.790265-14-sean.wang@kernel.org
Signed-off-by: Felix Fietkau <nbd@nbd.name>