The hardware tag-based KASAN for compatibility with the other modes
stores the tag associated to a page in page->flags.
Due to this the kernel faults on access when it allocates a page with an
initial tag and the user changes the tags.

Reset the tag associated by the kernel to a page in all the meaningful
places to prevent kernel faults on access.

Note: An alternative to this approach could be to modify page_to_virt().
This though could end up being racy, in fact if a CPU checks the
PG_mte_tagged bit and decides that the page is not tagged but another
CPU maps the same with PROT_MTE and becomes tagged the subsequent kernel
access would fail.

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>