V4L/DVB (11669): uvc: fix compile warning

The 2.6.30 kernel generates this warning:

uvc_driver.c:1729: warning: 'ret' may be used uninitialized in this function

I guess some new warning flag must have been turned on since this warning
didn't appear with older kernels (gcc version 4.3.1). It's also a bogus
warning, but since this code didn't comply to the coding standard anyway
I've modified it to 1) remove the warning and 2) conform to the coding
standard.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>