V4L/DVB (13622): gspca - ov534: Fix a compilation warning.

This warning prevented the sharpness setting to work with the ov965x sensor.

Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jean-Francois Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>