Let's have the following variants for destroying pages:

(1) uv_destroy(): Like uv_pin_shared() and uv_convert_from_secure(),
"low level" helper that operates on paddr and doesn't mess with folios.

(2) uv_destroy_folio(): Consumes a folio to which we hold a reference.

(3) uv_destroy_pte(): Consumes a PTE that holds a reference through the
mapping.

Unfortunately we need uv_destroy_pte(), because pfn_folio() and
friends are not available in pgtable.h.
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/20240508182955.358628-8-david@redhat.comSigned-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>