Staging: dt3155v4l: silence a compiler warning

The '!' is dead code that was left over from a previous version.
It causes a compiler warning:
drivers/staging/dt3155v4l/dt3155v4l.c:335:3: warning: value computed
	is not used

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>