* found some information about how to create board-bin files for wifi "ath10k" .. I hope it is same for "ath11k" .https://github.com/jhugo/linux/blob/5.5rc2_wifi/README
.But the main problem is for this build required "wlandsp" & "bdwlan" but in My device only available "bdwlan" firmwares.. "wlandsp" firmware also shown as symbolic link but not available on this location..

I was checked in
"/vendor/firmwares"
"/vendor/firmware_mnt"
"/odm/firmware"
But not available"wlandsp"

After that I found this linux-firmwars 
https://wireless.wiki.kernel.org/en/users/drivers/ath11k/installation

And I checked for "ath11k" firmware tree looking like this..

`./lib/firmware/ath11k/WCN6855/hw2.0/amss.bin
./lib/firmware/ath11k/WCN6855/hw2.0/board-2.bin
./lib/firmware/ath11k/WCN6855/hw2.0/m3.bin
./lib/firmware/ath11k/WCN6855/hw2.0/regdb.bin`

And required firmwares is 
"amss.bin, m3.bin, regdb.bin, board-2.bin"

And in my device available firmware are..
"amss20.bin, amss.bin, m3.bin, regdb.bin"