apparmor: Fix shadowed local variable in unpack_trans_table()

with W=2:

    security/apparmor/policy_unpack.c: In function ‘unpack_trans_table’:
    security/apparmor/policy_unpack.c:469: warning: declaration of ‘pos’ shadows a previous local
    security/apparmor/policy_unpack.c:451: warning: shadowed declaration is here

Rename the old "pos" to "saved_pos" to fix this.

Fixes: 5379a331

 ("apparmor: support v7 transition format compatible with label_parse")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>