xen/arm: rename DEVICE_PCI to DEVICE_PCI_HOSTBRIDGE

xen/arm: rename DEVICE_PCI to DEVICE_PCI_HOSTBRIDGE

To better reflect the nature of the device type and not to make any
confusion rename DEVICE_PCI to DEVICE_PCI_HOSTBRIDGE which it
really is.

Suggested-by: Julien Grall <julien@xen.org>
Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Reviewed-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Henry Wang <Henry.Wang@arm.com>
Reviewed-by: Jiamei xie <jiamei.xie@arm.com>
Reviewed-by: Rahul Singh <rahul.singh@arm.com>
Tested-by: Rahul Singh <rahul.singh@arm.com>