arm: rmobile: lager: Add external RAM boot

If CONFIG_RMOBILE_EXTRAM_BOOT is enabled, U-Boot is booted from External RAM.
The default boot address is 0xB0000000.

Signed-off-by: Hisashi Nakamura <hisashi.nakamura.ak@renesas.com>
Signed-off-by: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com>
Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
diff --git a/arch/arm/cpu/armv7/rmobile/Kconfig b/arch/arm/cpu/armv7/rmobile/Kconfig
index c46a0cc..75e38ea 100644
--- a/arch/arm/cpu/armv7/rmobile/Kconfig
+++ b/arch/arm/cpu/armv7/rmobile/Kconfig
@@ -23,6 +23,11 @@
 config SYS_SOC
 	default "rmobile"
 
+config RMOBILE_EXTRAM_BOOT
+	bool "Enable boot from RAM"
+	depends on TARGET_LAGER
+	default n
+
 source "board/atmark-techno/armadillo-800eva/Kconfig"
 source "board/renesas/koelsch/Kconfig"
 source "board/renesas/lager/Kconfig"