st/va: declare vlVaBuffer before vlVaContext

And declare coded_buf in vlVaContext as "vlVaBuffer *" instead of
"struct vlVaBuffer *".

This fixes several warnings later about assignment from incompatible
pointer type.

Reviewed-by: Emil Velikov <emil.velikov@collabora.com>

src/gallium/state_trackers/va/va_private.h

@@ -220,6 +220,20 @@ typedef struct {
    struct pipe_sampler_view *sampler;
 } vlVaSubpicture;
 
+typedef struct {
+   VABufferType type;
+   unsigned int size;
+   unsigned int num_elements;
+   void *data;
+   struct {
+      struct pipe_resource *resource;
+      struct pipe_transfer *transfer;
+   } derived_surface;
+   unsigned int export_refcount;
+   VABufferInfo export_state;
+   unsigned int coded_size;
+} vlVaBuffer;
+
 typedef struct {
    struct pipe_video_codec templat, *decoder;
    struct pipe_video_buffer *target;
@@ -243,7 +257,7 @@ typedef struct {
    } mpeg4;
 
    struct vl_deint_filter *deint;
-   struct vlVaBuffer *coded_buf;
+   vlVaBuffer *coded_buf;
    int target_id;
    bool first_single_submitted;
    int gop_coeff;
@@ -256,20 +270,6 @@ typedef struct {
    unsigned int rt_format;
 } vlVaConfig;
 
-typedef struct {
-   VABufferType type;
-   unsigned int size;
-   unsigned int num_elements;
-   void *data;
-   struct {
-      struct pipe_resource *resource;
-      struct pipe_transfer *transfer;
-   } derived_surface;
-   unsigned int export_refcount;
-   VABufferInfo export_state;
-   unsigned int coded_size;
-} vlVaBuffer;
-
 typedef struct {
    struct pipe_video_buffer templat, *buffer;
    struct util_dynarray subpics; /* vlVaSubpicture */