calib: Enable I2C GPIO expanders connected via BBB's I2C

Change-Id: I057183fe756a45bf53e4eaeed5bb8d88a702700b
diff --git a/board/czechlight/beaglebone/linux.fragment b/board/czechlight/beaglebone/linux.fragment
index 2871883..d4b75f3 100644
--- a/board/czechlight/beaglebone/linux.fragment
+++ b/board/czechlight/beaglebone/linux.fragment
@@ -1 +1,4 @@
 CONFIG_OMAP_WATCHDOG=y
+
+# calibration device
+CONFIG_PINCTRL_MCP23S08=y