Correct joystick hat indexes on linux

The index and indices were swapped; Which is fine as long as there are
no gaps in the ABS_HAT* event availability but otherwise things do get confused.

Signed-off-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>

src/joystick/linux/SDL_sysjoystick.c

@@ -727,7 +727,7 @@ ConfigJoystick(SDL_Joystick * joystick, int fd)
                        absinfo.value, absinfo.minimum, absinfo.maximum,
                        absinfo.fuzz, absinfo.flat);
 #endif /* DEBUG_INPUT_EVENTS */
-                joystick->hwdata->hats_indices[joystick->nhats++] = hat_index;
+                joystick->hwdata->hats_indices[hat_index] = joystick->nhats++;
             }
         }
         if (test_bit(REL_X, relbit) || test_bit(REL_Y, relbit)) {