Source correct module's `init.zsh`

Now that modules can be located in different directories, the `init.zsh` should be loaded from the `$module_location` and not `$ZPREZTODIR/modules/$pmodule`

init.zsh

@@ -123,8 +123,8 @@ function pmodload {
         done
       }
 
-      if [[ -s "$ZPREZTODIR/modules/$pmodule/init.zsh" ]]; then
-        source "$ZPREZTODIR/modules/$pmodule/init.zsh"
+      if [[ -s "${pmodule_location}/init.zsh" ]]; then
+        source "${pmodule_location}/init.zsh"
       fi
 
       if (( $? == 0 )); then