[yocto] [meta-raspberrypi][PATCH V4 12/14] rpi-default-versions.inc: Use fallback weak assignment

[Khem Raj]

This lets machines use ?= to choose their preferred kernel
e.g. 64bit rpi3 needs 4.9 minimum but default right now
is 4.4

At the same time it keeps the option for user to override
any of these settings via config metadata e.g. local.conf

Signed-off-by: Khem Raj <raj.khem at gmail.com>
---
 conf/machine/include/rpi-default-versions.inc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/conf/machine/include/rpi-default-versions.inc b/conf/machine/include/rpi-default-versions.inc
index e65a4ae..2007cc0 100644
--- a/conf/machine/include/rpi-default-versions.inc
+++ b/conf/machine/include/rpi-default-versions.inc
@@ -1,3 +1,3 @@
 # RaspberryPi BSP default versions
 
-PREFERRED_VERSION_linux-raspberrypi ?= "4.4.%"
+PREFERRED_VERSION_linux-raspberrypi ??= "4.4.%"
-- 
2.11.1