st/xvmc: Fix compiler warnings

Mostly signed/unsigned comparison

Signed-off-by: Jan Vesely <jan.vesely@rutgers.edu>
Reviewed-by: Christian König <christian.koenig@amd.com>
diff --git a/src/gallium/state_trackers/xvmc/xvmc_private.h b/src/gallium/state_trackers/xvmc/xvmc_private.h
index eaf388a..84c7b6c 100644
--- a/src/gallium/state_trackers/xvmc/xvmc_private.h
+++ b/src/gallium/state_trackers/xvmc/xvmc_private.h
@@ -69,7 +69,7 @@
    struct pipe_video_buffer *video_buffer;
 
    /* nonzero if this picture is already being decoded */
-   int picture_structure;
+   unsigned picture_structure;
 
    XvMCSurface *ref[2];
 
@@ -106,7 +106,7 @@
 #define XVMC_WARN  2
 #define XVMC_TRACE 3
 
-static INLINE void XVMC_MSG(unsigned int level, const char *fmt, ...)
+static INLINE void XVMC_MSG(int level, const char *fmt, ...)
 {
    static int debug_level = -1;