xen/arm: optee: Allocate anonymous domheap pages

xen/arm: optee: Allocate anonymous domheap pages

Allocate anonymous domheap pages as there is no strict need to
account them to a particular domain.

Since XSA-383 "xen/arm: Restrict the amount of memory that dom0less
domU and dom0 can allocate" the dom0 cannot allocate memory outside
of the pre-allocated region. This means if we try to allocate
non-anonymous page to be accounted to dom0 we will get an
over-allocation issue when assigning that page to the domain.
The anonymous page, in turn, is not assigned to any domain.

CC: Julien Grall <jgrall@amazon.com>
Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Acked-by: Volodymyr Babchuk <volodymyr_babchuk@epam.com>
Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>
Acked-by: Julien Grall <jgrall@amazon.com>