dm crypt: account large pages in cc->n_allocated_pages

The commit 5054e778 ("dm crypt: allocate compound pages if
possible") changed dm-crypt to use compound pages to improve
performance. Unfortunately, there was an oversight: the allocation of
compound pages was not accounted at all. Normal pages are accounted in
a percpu counter cc->n_allocated_pages and dm-crypt is limited to
allocate at most 2% of memory. Because compound pages were not
accounted at all, dm-crypt could allocate memory over the 2% limit.

Fix this by adding the accounting of compound pages, so that memory
consumption of dm-crypt is properly limited.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Fixes: 5054e778 ("dm crypt: allocate compound pages if possible")
Cc: stable@vger.kernel.org	# v6.5+
Signed-off-by: Mike Snitzer <snitzer@kernel.org>