Use tr(1) to lowercase strings in a way which works with all locales.

Approved by:	cperciva (mentor)

tools/tools/nanobsd/FlashDevice.sub

@@ -38,8 +38,8 @@
 
 sub_FlashDevice () {
 
-	a1=`echo $1 | tr '[A-Z]' '[a-z]'` 
-	a2=`echo $2 | tr '[A-Z]' '[a-z]'` 
+	a1=`echo $1 | tr '[:upper:]' '[:lower:]'`
+	a2=`echo $2 | tr '[:upper:]' '[:lower:]'`
 	case $a1 in
 	integral)
 		# Source: mich@FreeBSD.org