kfence: fix KASAN HW tags bypass via runtime sample_interval change

kfence: fix KASAN HW tags bypass via runtime sample_interval change

If a user writes a non-zero value to the sample_interval module parameter
at runtime, the missing KASAN HW tags check in the late init path allows
KFENCE to be enabled alongside KASAN HW tags, bypassing the boot
restriction.

This patch adds the missing check to param_set_sample_interval() to reject
the parameter change if KASAN HW tags are enabled.

Link: https://lore.kernel.org/20260507095237.741017-1-glider@google.com
Fixes: 09833d99db36 ("mm/kfence: disable KFENCE upon KASAN HW tags enablement")
Signed-off-by: Alexander Potapenko <glider@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Pimyn Girgis <pimyn@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>