media: pvrusb2: qctrl.flag will be uninitlaized if cx2341x_ctrl_query() returns error code

Inside function ctrl_cx2341x_getv4lflags(), qctrl.flag
will be uninitlaized if cx2341x_ctrl_query() returns -EINVAL.
However, it will be used in the later if statement, which is
potentially unsafe.

Signed-off-by: Yizhuo <yzhai003@ucr.edu>
Acked-by: Mike Isely <isely@pobox.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>