[media] staging/media/solo6x10/v4l2-enc.c: fix error-handling

The return values of copy_to_user() and copy_from_user() cannot be negative.
Found using the following semantich patch:
<spml>
@exists@
identifier ret;
statement S;
expression E;
@@
(
* ret = copy_to_user(...);
|
* ret = copy_from_user(...);
)
... when != ret = E
    when != if (ret) { <+... ret = E; ...+> }
* if (ret < 0)
  S
</spml>
Signed-off-by: Cyril Roelandt <tipecaml@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/staging/media/solo6x10/v4l2-enc.c

@@ -1619,6 +1619,8 @@ static int solo_s_ext_ctrls(struct file *file, void *priv,
 				solo_enc->osd_text[OSD_TEXT_MAX] = '\0';
 				if (!err)
 					err = solo_osd_print(solo_enc);
+				else
+					err = -EFAULT;
 			}
 			break;
 		default:
@@ -1654,6 +1656,8 @@ static int solo_g_ext_ctrls(struct file *file, void *priv,
 				err = copy_to_user(ctrl->string,
 						   solo_enc->osd_text,
 						   OSD_TEXT_MAX);
+				if (err)
+					err = -EFAULT;
 			}
 			break;
 		default: