Commit a0b032ad85 (package/qemu: security bump to version 3.1.1)
bumped the version but didn't update the patch subdirectory name, so the
patches are now ignored.
Fix that by renaming the directory. Drop
0002-configure-improve-usbfs-check.patch as that is now upstream.
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>