Getting wifi to work on RPI4 : dtb files and location

[Mayuresh <mayuresh%acm.org@localhost>]

I have Jun's 22 Jul image for RPI4 on which wifi is working.

I have aarch64 daily build of 08Aug on which wifi is not working.

Following is the difference in the dmesg:

Jun's image:

    bwfm0: Found NVRAM file: brcmfmac43455-sdio.Raspberry Pi 4 Model B.txt

08 Aug image:

    bwfm0: autoconfiguration error: NVRAM file not available

Copying bcm2711-rpi-4* from /boot of Jun's image to /boot of 08Aug image
did not help. The 08Aug image has these files (though of different size)
in dtb folder.

What exactly do I need to do so that it finds the NVRAM file?

-- 
Mayuresh