[KERNEL][VERSION] Update preferrred version for C31

* Update preferred kernel version to 5.10 for C31
* Add comment to make the kernel version forcing reason for some of the
  boards more explanatory

scripts/get_kernel_version.sh

@@ -5,9 +5,13 @@ PREFERRED_KERNEL=$(bitbake virtual/kernel -e | grep ^PREFERRED_PROVIDER_virtual/
 KERNEL_VERSION=$(bitbake virtual/kernel -e | grep ^PREFERRED_VERSION_${PREFERRED_KERNEL} | awk -F'=' '{print $2}' | sed 's/\"//g' | head -1)
 kernel_version="$(echo ${KERNEL_VERSION%\%} | sed 's/\./-/g')"
 
+# Some of the boards inside Edgehog does not have 
+# a valid value of KERNEL_VERSION variable so we
+# need to force its value as long as bug fixes are
+# not performed
 case "$BOARD" in
     *"c31"*)
-        kernel_version="4-19"
+        kernel_version="5-10"
         ;;
     *"tanaro"*)
         kernel_version="5-10"