Add SPI flash driver

This driver is taken from u-boot and adapted to match
coreboot. It still contains some hacks and is ICH specific
at places.

Change-Id: I97dd8096f7db3b62f8f4f4e4d08bdee10d88f689
Signed-off-by: Patrick Georgi <patrick@georgi-clan.de>
Reviewed-on: http://review.coreboot.org/997
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
diff --git a/src/Kconfig b/src/Kconfig
index a6b09dc..a5a0f00 100644
--- a/src/Kconfig
+++ b/src/Kconfig
@@ -946,6 +946,13 @@
 	help
 	  This option enables additional TPM related debug messages.
 
+config DEBUG_SPI_FLASH
+	bool "Output verbose SPI flash debug messages"
+	default n
+	depends on SPI_FLASH
+	help
+	  This option enables additional SPI flash related debug messages.
+
 if SOUTHBRIDGE_INTEL_BD82X6X && DEFAULT_CONSOLE_LOGLEVEL_8
 # Only visible with the right southbridge and loglevel.
 config DEBUG_INTEL_ME