set_phys_to_machine can fail due to lack of memory, see the kzalloc call
in arch/arm/xen/p2m.c:__set_phys_to_machine_multi.

Don't ignore the potential return error in set_foreign_p2m_mapping,
returning it to the caller instead.

This is part of XSA-361.
Signed-off-by: NStefano Stabellini <stefano.stabellini@xilinx.com>
Cc: stable@vger.kernel.org
Reviewed-by: NJulien Grall <jgrall@amazon.com>
Signed-off-by: NJuergen Gross <jgross@suse.com>