avcodec/adpcm_data: use uint16_t to handle all values

Signed-off-by: Paul B Mahol <onemda@gmail.com>

libavcodec/adpcm_data.c

@@ -106,7 +106,7 @@ const int8_t ff_adpcm_yamaha_difflookup[] = {
     -1, -3, -5, -7, -9, -11, -13, -15
 };
 
-const int16_t ff_adpcm_afc_coeffs[2][16] = {
+const uint16_t ff_adpcm_afc_coeffs[2][16] = {
     { 0, 2048, 0, 1024, 4096, 3584, 3072, 4608, 4200, 4800, 5120, 2048, 1024, 64512, 64512, 63488 },
     { 0, 0, 2048, 1024, 63488, 64000, 64512, 62976, 63288, 63236, 62464, 63488, 64512, 1024, 0, 0 }
 };