xen/ioreq: Make x86's hvm_ioreq_needs_completion() common

xen/ioreq: Make x86's hvm_ioreq_needs_completion() common

The IOREQ is a common feature now and this helper will be used
on Arm as is. Move it to xen/ioreq.h and remove "hvm" prefix.

Although PIO handling on Arm is not introduced with the current series
(it will be implemented when we add support for vPCI), technically
the PIOs exist on Arm (however they are accessed the same way as MMIO)
and it would be better not to diverge now.

Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Acked-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Julien Grall <jgrall@amazon.com>
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>