ACPI: pci_root: Unify the message printing

In acpi_pci_root_add(), pr_info() is added with PREFIX, but
in acpi_pci_root_remap_iospace() the pr_info() with no
PREFIX.

Introduce pr_fmt() to unify the message printing and remove
the PREFIX.

Signed-off-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>