PCI: Always set prefetchable base/limit upper32 registers

PCI: Always set prefetchable base/limit upper32 registers

commit 59353ea30e65ab3ae181d6175e3212e1361c3787 upstream.

Prior to 1f82de10 we always initialized the upper 32bits of the
prefetchable memory window, regardless of the address range used.
Now we only touch it for a >32bit address, which means the upper32
registers remain whatever the BIOS initialized them too.

It's valid for the BIOS to set the upper32 base/limit to
0xffffffff/0x00000000, which makes us program prefetchable ranges
like 0xffffffffabc00000 - 0x00000000abc00000

Revert the chunk of 1f82de10 that made this conditional so we always
write the upper32 registers and remove now unused pref_mem64 variable.

Signed-off-by: Alex Williamson <alex.williamson@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Rafael J. Wysocki <rjw@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>