test: Fix incomplete line in .x file

A line in tst.stack_fbt.x had been put back mysteriously chopped off,
causing the script to fail and tst.stack_fbt.d and tst.stack3_fbt.d
to be skipped inadvertently.

Signed-off-by: Eugene Loh <eugene.loh@oracle.com>
Reviewed-by: Kris Van Hees <kris.van.hees@oracle.com>

test/unittest/stack/tst.stack_fbt.x

@@ -1,6 +1,6 @@
 #!/bin/bash
 
-read MAJOR MINOR <<< `uname -r | grep -Eo '^[0-9]+\.[0-9]+'
+read MAJOR MINOR <<< `uname -r | grep -Eo '^[0-9]+\.[0-9]+' | tr '.' ' '`
 
 if [ $MAJOR -eq 5 -a $MINOR -lt 8 ]; then
 	exit 0