PCI/ACPI: Tidy up MCFG quirk whitespace

With no blank lines, it's not obvious where the macro definitions end and
the uses begin.  Add some blank lines and reorder the ThunderX definitions.
No functional change intended.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: stable@vger.kernel.org	# v4.10+