tools: Fix buildscript-bash-completion

The dynamic completion of the variants is broken since 1946aaca87.
This hardcodes the available variants. They won't change often.

Signed-off-by: Robert Langhammer <rlanghammer@web.de>

tools/buildscript-bash-completion

@@ -11,7 +11,7 @@ selectbsp)
 	COMPREPLY=($(compgen -W "$(find bsp -name '*.bsp')" "${COMP_WORDS[2]}"))
 	;;
 selectvariant)
-	COMPREPLY=($(compgen -W "$("${COMP_WORDS[0]}" "${COMP_WORDS[1]}" | sed '0,/available variants:/d')" "${COMP_WORDS[2]}"))
+	COMPREPLY=($(compgen -W "node layer3" "${COMP_WORDS[2]}"))
 	;;
 build)
 	COMPREPLY=($(compgen -W "fast debug" "${COMP_WORDS[2]}"))