Hyper-V: vPCI: Write back original BAR values after prepopulating bars

In vmbus_pcib_prepopulate_bars(), after writing all 1's to the
avialable device bars, those without being configured by device driver
are also set to its initialized values. However, this could cause
weird problem which results to device failure. The issue has been
reported to happen on LSI 9211-8i HBA card for DDA access on Hyper-V.
Writing back the orignal BAR values seem to work around this problem.

Reported by: Alexander Motin <mavbsd@gmail.com>
Tested by: Mathias Kraut <krautmaster@gmail.com>
Fixes: 75412a521f6 Hyper-V: vPCI: Prepopulate device bars
MFC after: 1 month