scripts/mod/modpost.c: fix commentary accordingly to last changes

The last commits
 37ed19d5
 5003bab8
have introduced new behaviour of sec2annotation() method. However, the
commentary inside the method was left as before. Let's fix it accordingly.

Signed-off-by: Andy Shevchenko <ext-andriy.shevchenko@nokia.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andrew Morton <akpm@linux-foundation.org>
Acked-by: WANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>