usb: gadget: don't release an existing dev->buf

commit 89f3594d0de58e8a57d92d497dea9fee3d4b9cda upstream.
dev->buf does not need to be released if it already exists before
executing dev_config.

Issue: FP3SEC-397
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
Link: https://lore.kernel.org/r/20211231172138.7993-2-hbh25y@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit c13159a588818a1d2cd6519f4d3b6f7e17a9ffbd)
Change-Id: I96c30f66a01a78ee27e6dd70b17f6ccb0ca38171