linux-kunbus: Fix build by including missing default-cpu-governor.cfg

The linux-kunbus kernel recipe includes the file linux-raspberrypi.inc
which is present in the BSP layer. As such we also need to add here
the kernel config fragment(s) the BSP include file uses.

Changelog-entry: Fix revpi-connect-s build by including missing default-cpu-governor.cfg
Signed-off-by: Florin Sarbu <florin@balena.io>

layers/meta-balena-raspberrypi/recipes-kernel/linux-kunbus/linux-kunbus/default-cpu-governor.cfg

@@ -0,0 +1,9 @@
+# The defconfigs from the RPi Kernel set "powersave" as the default CPU governor.
+# That is a bad idea as it reduces performance, so we unset that default option here.
+# The option to build the powersave governor (but not as the default) is also enabled.
+# A fix for this was sent to upstream: https://github.com/raspberrypi/linux/pull/5666
+# However, we need to carry this option override until those defconfigs are fixed on
+# *all* the kernel branches that we support. So that can be a long time depending
+# on wheter the above PR gets accepted and/or backported to the stable branches.
+CONFIG_CPU_FREQ_DEFAULT_GOV_POWERSAVE=n
+CONFIG_CPU_FREQ_GOV_POWERSAVE=y