Convert CONFIG_SYS_USE_NORFLASH et al to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_USE_NORFLASH
   CONFIG_SYS_USE_BOOT_NORFLASH

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/board/atmel/at91sam9263ek/Kconfig b/board/atmel/at91sam9263ek/Kconfig
index 3f0873f..71cbc89 100644
--- a/board/atmel/at91sam9263ek/Kconfig
+++ b/board/atmel/at91sam9263ek/Kconfig
@@ -9,4 +9,7 @@
 config SYS_CONFIG_NAME
 	default "at91sam9263ek"
 
+config SYS_USE_NORFLASH
+	bool "Use the NOR flash on the platform"
+
 endif