ANDROID: mm, kasan: fix for "integrate page_alloc init with HW_TAGS"

My commit "integrate page_alloc init with HW_TAGS" changed the order of
kernel_unpoison_pages() and kernel_init_free_pages() calls. This leads
to complaints from the page unpoisoning code, as the poison pattern gets
overwritten for __GFP_ZERO allocations.

Fix by restoring the initial order. Also add a warning comment.

Reported-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Sergei Trofimovich <slyfox@gentoo.org>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Sergei Trofimovich <slyfox@gentoo.org>

The fix was included in upstream patch 1bb5eab3 'kasan, mm: integrate page_alloc init with HW_TAGS'

Fixes: a1598949 ("FROMGIT: kasan, mm: integrate page_alloc init with HW_TAGS")
Bug: 192912968
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Change-Id: Ifc4ab7ed27b3c060f70ba5ca03117a36c9b4da08