soc/intel/quark: Add I2C debugging

Add I2C debugging support:
* Add I2C_DEBUG Kconfig value to enable debugging
* Display I2C segments before the transfer
* Display errors that occur during the transfer
* Display the number of bytes transferred for successful transfers

TEST=Build and run on Galileo Gen2

Change-Id: Ia17be8b4213b13fd6c6a367d081414d0f21fbb0f
Signed-off-by: Lee Leahy <Leroy.P.Leahy@intel.com>
Reviewed-on: https://review.coreboot.org/20422
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin Roth <martinroth@google.com>
Reviewed-by: Sumeet R Pawnikar <sumeet.r.pawnikar@intel.com>

src/soc/intel/quark/Kconfig

@@ -316,4 +316,14 @@ config STORAGE_LOG
 	default n
 	depends on STORAGE_TEST
 
+#####
+# I2C debug support
+#####
+
+config I2C_DEBUG
+	bool "Enable I2C debugging"
+	default n
+	help
+	  Display the I2C segments and controller errors
+
 endif # SOC_INTEL_QUARK