USB: handle more rndis_host oddities

Workaround another device firmware bug, wherein CDC descriptors get
placed in a wrong place never previously observed in the wild.

Fix a bug where a seeming RNDIS device returns a bogus response during
device initialization.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>