balena-os.inc: Set PREFERRED_VERSION_linux-firmware to 20190815

We imported the linux-firmware recipe from Poky zeus-22.0.1 release (so
we are synced across all our supported boards) and now let's set it as
preferred version to make the build system use it.

Changelog-entry: Set PREFERRED_VERSION_linux-firmware to 20190815
Signed-off-by: Florin Sarbu <florin@balena.io>

meta-balena-common/conf/distro/include/balena-os.inc

@@ -90,5 +90,8 @@ BAD_RECOMMENDATIONS += "shared-mime-info"
 PREFERRED_VERSION_upx_arm = "3.94"
 PREFERRED_VERSION_upx-native_arm = "3.94"
 
+# let's pin linux-firmware to the version we imported from Poky zeus-22.0.1 release
+PREFERRED_VERSION_linux-firmware = "20190815"
+
 # balena-engine go version requirement
 GOVERSION = "1.10.8"