V4L/DVB (7328): usb/opera1.c: fix a memory leak

This patch fixes a memory leak in the "testval == 0x67" case spotted by
the Coverity checker.

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>