Add support for environment in SPI flash

This is pretty incomplete...it doesn't handle reading the environment
before relocation, it doesn't support redundant environment, and it
doesn't support embedded environment. But apart from that, it does
seem to work.

Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
diff --git a/common/cmd_nvedit.c b/common/cmd_nvedit.c
index 9c5d1fc..49f134a 100644
--- a/common/cmd_nvedit.c
+++ b/common/cmd_nvedit.c
@@ -58,8 +58,9 @@
     !defined(CFG_ENV_IS_IN_DATAFLASH)	&& \
     !defined(CFG_ENV_IS_IN_NAND)	&& \
     !defined(CFG_ENV_IS_IN_ONENAND)	&& \
+    !defined(CFG_ENV_IS_IN_SPI_FLASH)	&& \
     !defined(CFG_ENV_IS_NOWHERE)
-# error Define one of CFG_ENV_IS_IN_{NVRAM|EEPROM|FLASH|DATAFLASH|ONENAND|NOWHERE}
+# error Define one of CFG_ENV_IS_IN_{NVRAM|EEPROM|FLASH|DATAFLASH|ONENAND|SPI_FLASH|NOWHERE}
 #endif
 
 #define XMK_STR(x)	#x