avcodec/arm/vp8: Don't discard const

Forgotten in 25e1986e.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavcodec/arm/vp8.h

@@ -29,7 +29,8 @@
 #define vp8_decode_block_coeffs_internal ff_decode_block_coeffs_armv6
 int ff_decode_block_coeffs_armv6(VPXRangeCoder *rc, int16_t block[16],
                                  uint8_t probs[8][3][NUM_DCT_TOKENS-1],
-                                 int i, uint8_t *token_prob, int16_t qmul[2]);
+                                 int i, const uint8_t *token_prob,
+                                 const int16_t qmul[2]);
 #endif
 
 #endif /* AVCODEC_ARM_VP8_H */