[media] DaVinci-VPFE-Capture: fix error handling

A recent cleanup had the right idea to remove the initialization
of the error variable, but missed the actual benefit of that,
which is that we get warnings if there is a bug in it. Now
we get a warning about a bug that was introduced by this cleanup:

drivers/media/platform/davinci/vpfe_capture.c: In function 'vpfe_probe':
drivers/media/platform/davinci/vpfe_capture.c:1992:9: error: 'ret' may be used uninitialized in this function [-Werror=maybe-uninitialized]

This adds the missing initialization that the warning is about,
and another one that was preexisting and that we did not get
a warning for. That second bug has existed since the driver
was first added.

Fixes: efb74461 ("[media] DaVinci-VPFE-Capture: Delete an unnecessary variable initialisation in vpfe_probe()")
Fixes: 7da8a6cb ("V4L/DVB (12248): v4l: vpfe capture bridge driver for DM355 and DM6446")

[mchehab@s-opensource.com: fix a merge conflict]
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/platform/davinci/vpfe_capture.c

@@ -1966,6 +1966,7 @@ static int vpfe_probe(struct platform_device *pdev)
 			v4l2_info(&vpfe_dev->v4l2_dev,
 				  "v4l2 sub device %s register fails\n",
 				  sdinfo->name);
+			ret = -ENXIO;
 			goto probe_sd_out;
 		}
 	}