usb: gadget: composite: Fix corruption when changing configuration

Remove the config from the configs list before releasing the spinlock.
Otherwise the other cpu might be processing a SET_CONFIGURATION that
will switch to the configuration that is being released.

Change-Id: Id4da0d0e18ead63e20cb236cd1d3e8e6d116acce
Signed-off-by: Benoit Goby <benoit@android.com>