zephyr-env.sh: Use lowercase for internal vars

ci: run_ci: Use lowercase for internal variables

This makes it possible to tell at a glance which variables are internal
to the script and which ones are parameters to it, which is very
helpful.

This convention is pretty common. See e.g. Google's shell style guide at
https://google.github.io/styleguide/shell.xml#Naming_Conventions, and
https://github.com/icy/bash-coding-style#naming-and-styles. It's older
than those though.

Signed-off-by: Ulf Magnusson <Ulf.Magnusson@nordicsemi.no>

zephyr-env.sh

@@ -13,20 +13,20 @@
 # Note: The version of zsh need to be 5.0.6 or above. Any versions below
 # 5.0.6 maybe encoutner errors when sourcing this script.
 if [ -n "${ZSH_VERSION:-}" ]; then
-	DIR="${(%):-%N}"
+	dir="${(%):-%N}"
 	if [ $options[posixargzero] != "on" ]; then
 		setopt posixargzero
-		NAME=$(basename -- "$0")
+		name=$(basename -- "$0")
 		unsetopt posixargzero
 	else
-		NAME=$(basename -- "$0")
+		name=$(basename -- "$0")
 	fi
 else
-	DIR="${BASH_SOURCE[0]}"
-	NAME=$(basename -- "$0")
+	dir="${BASH_SOURCE[0]}"
+	name=$(basename -- "$0")
 fi
 
-if [ "X$NAME" "==" "Xzephyr-env.sh" ]; then
+if [ "X$name" "==" "Xzephyr-env.sh" ]; then
     echo "Source this file (do NOT execute it!) to set the Zephyr Kernel environment."
     exit
 fi
@@ -37,15 +37,15 @@ fi
 
 if uname | grep -q "MINGW"; then
     win_build=1
-    PWD_OPT="-W"
+    pwd_opt="-W"
 else
     win_build=0
-    PWD_OPT=""
+    pwd_opt=""
 fi
 
 # identify OS source tree root directory
-export ZEPHYR_BASE=$( builtin cd "$( dirname "$DIR" )" > /dev/null && pwd ${PWD_OPT})
-unset PWD_OPT
+export ZEPHYR_BASE=$( builtin cd "$( dirname "$dir" )" > /dev/null && pwd ${pwd_opt})
+unset pwd_opt
 
 scripts_path=${ZEPHYR_BASE}/scripts
 if [ "$win_build" -eq 1 ]; then