gru: kevin: enable EC SPI interface

This configures and enables SPI interface #5 used for EC
communications on Gru/Kevin.

BRANCH=none
BUG=chrome-os-partner:51537
TEST=with the appropriate depthcharge change it is possible to trigger
     booting Chrome OS from the SD card by pressing '^U' on Gru
     keyboard at the right time.

Change-Id: I5304bf47e030c0b9b7794752f30ffdca6c03a4f4
Signed-off-by: Martin Roth <martinroth@chromium.org>
Original-Commit-Id: b5cc177
Original-Change-Id: I99883daa60562ccddfaeb858c1957d497f05a501
Original-Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/346632
Reviewed-on: https://review.coreboot.org/15032
Tested-by: build bot (Jenkins)
Reviewed-by: Furquan Shaikh <furquan@google.com>
diff --git a/src/mainboard/google/gru/Kconfig b/src/mainboard/google/gru/Kconfig
index 48ae698..39cbf08 100644
--- a/src/mainboard/google/gru/Kconfig
+++ b/src/mainboard/google/gru/Kconfig
@@ -56,7 +56,7 @@
 
 config EC_GOOGLE_CHROMEEC_SPI_BUS
 	hex
-	default 0
+	default 5
 
 config BOOT_MEDIA_SPI_BUS
 	int