Cleanup unused y4m reference in rdopt

Change-Id: I0f33ffb7df5275859608d3c5d5bbe4c66ff09926
diff --git a/av1/encoder/rdopt.h b/av1/encoder/rdopt.h
index d4df1e8..f0b0b35 100644
--- a/av1/encoder/rdopt.h
+++ b/av1/encoder/rdopt.h
@@ -140,12 +140,6 @@
                    uint8_t *dst);
 
 /* Applies standard 3x3 Sobel matrix. */
-typedef struct y4m_input y4m_input;
-
-/*The function used to perform chroma conversion.*/
-typedef void (*y4m_convert_func)(y4m_input *_y4m, unsigned char *_dst,
-                                 unsigned char *_src);
-
 typedef struct {
   int16_t x;
   int16_t y;