swscale/yuv2rgb: Return a more specific error code from ff_yuv2rgb_c_init_tables()

Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libswscale/yuv2rgb.c

@@ -993,7 +993,7 @@ av_cold int ff_yuv2rgb_c_init_tables(SwsContext *c, const int inv_table[4],
     default:
         if(!isPlanar(c->dstFormat) || bpp <= 24)
             av_log(c, AV_LOG_ERROR, "%ibpp not supported by yuv2rgb\n", bpp);
-        return -1;
+        return AVERROR(EINVAL);
     }
     return 0;
 }