linux-firmware: disable stripping

linux-firmware: disable stripping

It has been brought to my attention that recently added WCN6855 firmware
is broken as it is getting stripped during building due to being 2 ELF
binaries.
I am sure WCN6750 and any other ELF binaries are having the same issue,
so since stripping firmware binaries is clearly unwanted disable it.

Fixes: b4d3694f81f4 ("linux-firmware: package ath11k consumer cards firmware")
Signed-off-by: Robert Marko <robimarko@gmail.com>
(cherry picked from commit 9d8eff6799469e2ed8a5d2e4decd194902c1ec1b)