i386: Remove unneeded test of 'task' in dump_trace()

Remove unneeded test of task != NULL from
arch/i386/kernel/traps.c::dump_trace()

At the start of the function we have this test:
        if (!task)
                task = current;
so further down there's no need to test 'task'.

Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>