wil6210: fix boot loader "ready" indication

Boot loader "ready" indication has changed from "bit0 set"
to "only bit0 set". This is to address hardware glitches.
Due to glitches, sometimes right after reset register reads
0xffffffff, or (rarely) other garbage.

Reflect this in the driver

Signed-off-by: Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>