usb: gadget: udc: remove pointer dereference after free

[ Upstream commit 1f459262b0e1649a1e5ad12fa4c66eb76c2220ce ]

Remove pointer dereference after free.

Addresses-Coverity-ID: 1091173
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>