xen/ioreq: Make x86's hvm_ioreq_(page/vcpu/server) structs common

xen/ioreq: Make x86's hvm_ioreq_(page/vcpu/server) structs common

The IOREQ is a common feature now and these structs will be used
on Arm as is. Move them to xen/ioreq.h and remove "hvm" prefixes.

Also there is no need to include public/hvm/dm_op.h by
asm-x86/hvm/domain.h anymore since #define NR_IO_RANGE_TYPES
(which uses XEN_DMOP_IO_RANGE_PCI) gets moved to another location.
Instead include it by 2 places (p2m-pt.c and p2m-ept.c) which
require that header, but don't directly include it so far.

Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
CC: Julien Grall <julien.grall@arm.com>
[On Arm only]
Tested-by: Wei Chen <Wei.Chen@arm.com>