clearfog: Add two MCP23S17 GPIO expanders

FIXME: This needs a kernel patch for proper CS GPIO on Orion. Without
that patch, the CS-GPIO feature would end up activating HW GPIO#0, which
is wrong.

FIXME: This needs a kernel patch for the irq-open-drain operation, too.

Change-Id: I2715304ddc013beb625a5cbbebf0fd97f305c9d1
diff --git a/board/czechlight/clearfog/linux.fragment b/board/czechlight/clearfog/linux.fragment
index 724d3c5..83cd006 100644
--- a/board/czechlight/clearfog/linux.fragment
+++ b/board/czechlight/clearfog/linux.fragment
@@ -17,3 +17,6 @@
 
 # Extra I2C bus for the PSUs
 CONFIG_I2C_GPIO=y
+
+# SPI GPIO expander
+CONFIG_PINCTRL_MCP23S08=y