qemu: fix CVE-2021-20263

virtiofs: drop remapped security.capability xattr as needed

Signed-off-by: Sakib Sajal <sakib.sajal@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 7ad71de8)
Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>