usb: musb: Get the musb_qh poniter after musb_giveback

When multiple threads are performing USB transmission, musb->lock will be
unlocked when musb_giveback is executed. At this time, qh may be released
in the dequeue process in other threads, resulting in a wild pointer, so
it needs to be here get qh again, and judge whether qh is NULL, and when
dequeue, you need to set qh to NULL.

Fixes: dbac5d07

 ("usb: musb: host: don't start next rx urb if current one failed")
Cc: stable@vger.kernel.org
Signed-off-by: Xingxing Luo <xingxing.luo@unisoc.com>
Link: https://lore.kernel.org/r/20230919033055.14085-1-xingxing.luo@unisoc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>