Vfio: Ignore vfio device's multifunction flag
Vfio: Ignore vfio device's multifunction flag

PciRoot doesn't support multifunciion which forward pci config r/w
from function > 0 to function 0, so if the vfio device have multifunction
flag, guest will find the existence of all the other functions, actually it
is from the function 0. In order to fix these extra functions, this
patch clear the multifunction flag, so guest won't probe the other
functions.

BUG=chromium:992270
TEST=pass through a device with multifunction into guest

Change-Id: I395636411e0d7d2a3729de16e638d7f6b2dde552
Signed-off-by: Xiong Zhang <887154684953c1d7bc9f653d05b20c8de98c15bc@intel.corp-partner.google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/1954221
Tested-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Reviewed-by: Daniel Verkamp <72bc170b46ec491f7bdd4359a1c0bfed274de40c@chromium.org>

google/crosvm,google/crosvm,google/crosvm,google/crosvm