ktest: Take submenu into account for grub2 menus

grub-reboot selects the submenu's first menuentry (title is "1>0") rather than ktest's
menuentry (title is "2") by mistake.

===
$ sudo cat /boot/grub/grub.cfg | grep -E "^menuentry|^submenu"
...
menuentry 'Ubuntu' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option '...' {
...
submenu 'Advanced options for Ubuntu' $menuentry_id_option '...' {
...
menuentry 'ktest' {
...
===

Correct it by taking submenu entries into account in get_grub2_index().

Link: http://lkml.kernel.org/r/[e-mail]

Signed-off-by: Satoru Takeuchi <[e-mail]>
Signed-off-by: Steven Rostedt (VMware) <[e-mail]>

tools/testing/ktest/ktest.pl

···
 	    $grub_number++;
 	    $found = 1;
 	    last;
-	} elsif (/^menuentry\s/) {
+	} elsif (/^menuentry\s|^submenu\s/) {
 	    $grub_number++;
 	}
     }