more timing issue fixing

- add another usleep() to take care of LiDE 1110/210 scan issue on some
	hardware (fast ones ?).

ChangeLog

@@ -1,3 +1,8 @@
+2015-08-06 Stéphane Voltz <stef.dev@free.fr>
+	*  backend/genesys_devices.c, backend/genesys_gl841.c, backend/genesys_low.c:
+	fix GPIO setup for LiDE 33/40/50, add more usleep() for GL847
+	scanning issues. Some GL841 LEDADD improvements.
+
 2015-07-31 Stéphane Voltz <stef.dev@free.fr>
 	* frontend/tstbackend.c: add an option to do tests scans during
 	open/close tests.

backend/genesys_low.c

@@ -943,13 +943,18 @@ sanei_genesys_get_triple(Genesys_Register_Set *regs, uint16_t addr, uint32_t *va
   return SANE_STATUS_GOOD;
 }
 
-/* Checks if the scan buffer is empty */
+/** @brief Check if the scanner's internal data buffer is empty
+ * @param *dev device to test for data
+ * @param *empty return value
+ * @return empty will be set to SANE_TRUE if there is no scanned data.
+ **/
 SANE_Status
 sanei_genesys_test_buffer_empty (Genesys_Device * dev, SANE_Bool * empty)
 {
   uint8_t val = 0;
   SANE_Status status;
 
+  usleep(1000);
   status = sanei_genesys_get_status (dev, &val);
   if (status != SANE_STATUS_GOOD)
     {