iommu/amd: Don't clear DTE flags when modifying it

iommu/amd: Don't clear DTE flags when modifying it

Orabug: 22623807

commit cbf3ccd09d683abf1cacd36e3640872ee912d99b upstream.

During device assignment/deassignment the flags in the DTE
get lost, which might cause spurious faults, for example
when the device tries to access the system management range.
Fix this by not clearing the flags with the rest of the DTE.

Reported-by: G. Richard Bellamy <rbellamy@pteradigm.com>
Tested-by: G. Richard Bellamy <rbellamy@pteradigm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 11d9bb923f7f15361313e6f52bcd6dac0ebbe117)
Signed-off-by: Dan Duval <dan.duval@oracle.com>