x86/pci: Reword ECAM EfiMemoryMappedIO logging to avoid 'reserved'

x86/pci: Reword ECAM EfiMemoryMappedIO logging to avoid 'reserved'

fd3a8cff4d4a ("x86/pci: Treat EfiMemoryMappedIO as reservation of ECAM
space") added the concept of using the EFI memory map to help decide
whether ECAM space mentioned in the MCFG table is valid.

Unfortunately it described that EfiMemoryMappedIO space as "reserved", but
it is actually not *reserved* by the EFI memory map.  EfiMemoryMappedIO
only means the firmware requested that the OS map this space for use by
firmware runtime services.

Change the dmesg logging to describe it as simply "EfiMemoryMappedIO", not
as "reserved as EfiMemoryMappedIO".  A previous commit actually *does*
reserve the space if ACPI PNP0C01/02 devices haven't done so:

  - PCI: ECAM at [mem 0xe0000000-0xefffffff] reserved as EfiMemoryMappedIO
  + PCI: ECAM at [mem 0xe0000000-0xefffffff] is EfiMemoryMappedIO; assuming valid
    PCI: ECAM [mem 0xe0000000-0xefffffff] reserved to work around lack of ACPI motherboard _CRS

Link: https://lore.kernel.org/r/20231121183643.249006-3-helgaas@kernel.org
Tested-by: Tomasz Pala <gotar@polanet.pl>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>