REDHAT-BUG-2493709: Medium severity Linux Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved:

vfio/pci: Clean up DMABUFs before disabling function

On device shutdown, make vfiopcicoreclosedevice() call vfiopcidmabufcleanup() before the function is disabled via vfiopcicoredisable(). This ensures that all access via DMABUFs is revoked before the function's BARs become inaccessible.

This fixes an issue where, if the function is disabled first, a tiny window exists in which the function's MSE is cleared and yet BARs could still be accessed via the DMABUF. The resources would also be freed and up for grabs by a different driver.