kselftest: ftrace: Fix to compare a zero-filled hex value

Fix to compare a zero-filled hexadecimal value with a part of
string of long hexadecimal value.

In check_types(), the last part of testcase compares with
the hex value formatted by "%x" with a part of a string of
long hex value (trimmed by tail -c and head -c). However,
if that part of long hex value contains zero (e.g. "05" of
"a3082059"), printf generated value (e.g. "5") is diffrent
string, and the test case failed.

To fix this, pass "%02x" instead of "%x" to printf.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>

tools/testing/selftests/ftrace/test.d/kprobe/kprobe_args_type.tc

@@ -26,7 +26,7 @@ check_types() {
   test $X2 = $X3
   test 0x$X3 = $3
 
-  B4=`printf "%x" $4`
+  B4=`printf "%02x" $4`
   B3=`echo -n $X3 | tail -c 3 | head -c 2`
   test $B3 = $B4
 }