SPI Flash subsystem

This adds a new SPI flash subsystem.

Currently, only AT45 DataFlash in non-power-of-two mode is supported,
but some preliminary support for other flash types is in place as
well.

Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
diff --git a/Makefile b/Makefile
index 30b6aef..cc988e1 100644
--- a/Makefile
+++ b/Makefile
@@ -224,6 +224,7 @@
 LIBS += drivers/mtd/nand/libnand.a
 LIBS += drivers/mtd/nand_legacy/libnand_legacy.a
 LIBS += drivers/mtd/onenand/libonenand.a
+LIBS += drivers/mtd/spi/libspi_flash.a
 LIBS += drivers/net/libnet.a
 LIBS += drivers/net/sk98lin/libsk98lin.a
 LIBS += drivers/pci/libpci.a
@@ -390,6 +391,7 @@
 TAG_SUBDIRS += drivers/mtd/nand
 TAG_SUBDIRS += drivers/mtd/nand_legacy
 TAG_SUBDIRS += drivers/mtd/onenand
+TAG_SUBDIRS += drivers/mtd/spi
 TAG_SUBDIRS += drivers/net
 TAG_SUBDIRS += drivers/net/sk98lin
 TAG_SUBDIRS += drivers/pci