usb-storage: separate dynamic flags from fixed flags

This patch (as1089) separates out the dynamic atomic bitflags and the
static bitfields in usb-storage.  Until now the two sorts of flags
have been sharing the same word; this has always been awkward.

To help prevent possible confusion, the two new fields each have a
different name from the original.  us->fflags contains the fixed
bitfields (mostly taken from the USB ID table in unusual_devs.h), and
us->dflags contains the dynamic atomic bitflags (used with set_bit,
test_bit, and so on).

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: Matthew Dharm <mdharm-usb@one-eyed-alien.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>