USB: gadget: dummy_hcd.c: fix nested switch statements

Fix a messed up combination of two nested switch statements in
drivers/usb/gadget/dummy_hcd.c.

According to the USB spec (section 5.8.3) the maximum packet size for bulk
endpoints can be 512 for high-speed devices and 8, 16, 32 or 64 for full-speed
devices.  Low-speed devices must not have bulk endpoints.

Signed-off-by: Ingo van Lil <inguin@gmx.de>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>