kmsdrm: let device indexes be > 2 digits.

src/video/kmsdrm/SDL_kmsdrmvideo.c

@@ -82,7 +82,7 @@ get_driindex(void)
     hint = SDL_GetHint(SDL_HINT_KMSDRM_DEVICE_INDEX);
     if (hint) {
         const int idx = SDL_atoi(hint);
-        if ((idx >= 0) && (idx < 99)) {
+        if (idx >= 0) {
             return idx;  /* we'll take the user's request here. */
         }
     }