usb: gadget: composite: Fix NULL pointer crash in USB compliance test

usb: gadget: composite: Fix NULL pointer crash in USB compliance test

On the DXR2 board (AM335x using MUSB) the USB compliance test suite
(USB 2.0 Command Verifier) will cause the board to crash and reset
upon the "BOS Descriptor Test - Addressed state". Here the output
from the DRX2 while running this test:

GADGET DRIVER: usb_dnl_dfu
musb-hdrc: peripheral reset irq lost!
composite_setup (776)
data abort
pc : [<87f693ac>]          lr : [<87f6911c>]
sp : 86f33a58  ip : 00000000     fp : 86f3bbac
r10: 00000f00  r9 : 86f33ef4     r8 : 86f37da8
r7 : 00000005  r6 : 86f33a90     r5 : 00000000  r4 : 86f37e30
r3 : 00000000  r2 : 00000000     r1 : 87f9c888  r0 : 00000016
Flags: Nzcv  IRQs off  FIQs on  Mode SVC_32
Resetting CPU ...

resetting ...

By adding the case statement for USB_DT_BOS and therefore not running
into the default case (jump to unkown label) this crash is fixed.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Roger Meier <r.meier@siemens.com>
Cc: Samuel Egli <samuel.egli@siemens.com>
Cc: Enrico Leto <enrico.leto@siemens.com>
Acked-by: Heiko Schocher <hs@denx.de>
Cc: Lukasz Majewski <l.majewski@samsung.com>
Cc: Marek Vasut <marex@denx.de>