linux-dmabuf: Keep checking planes even if the first doesn't support lseek

If we break; when lseek fails we can fail to do some legitimate tests
on remaining planes in a multi-plane buffer.

Signed-off-by: Derek Foreman <derekf@osg.samsung.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>
diff --git a/src/linux-dmabuf.c b/src/linux-dmabuf.c
index 8c6337c..78e77a2 100644
--- a/src/linux-dmabuf.c
+++ b/src/linux-dmabuf.c
@@ -219,7 +219,7 @@
 		 * by the kernel not supporting seeking on dmabuf */
 		size = lseek(buffer->attributes.fd[i], 0, SEEK_END);
 		if (size == -1)
-			break;
+			continue;
 
 		if (buffer->attributes.offset[i] >= size) {
 			wl_resource_post_error(params_resource,