Convert CONFIG_CMD_SAVES to Kconfig

This converts the following to Kconfig:
   CONFIG_CMD_SAVES

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 9cfeede..c6f5f23 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -308,6 +308,7 @@
 config ARCH_DAVINCI
 	bool "TI DaVinci"
 	select CPU_ARM926EJS
+	imply CMD_SAVES
 	help
 	  Support for TI's DaVinci platform.
 
@@ -409,21 +410,25 @@
 	bool "Support spear300"
 	select CPU_ARM926EJS
 	select BOARD_EARLY_INIT_F
+	imply CMD_SAVES
 
 config TARGET_SPEAR310
 	bool "Support spear310"
 	select CPU_ARM926EJS
 	select BOARD_EARLY_INIT_F
+	imply CMD_SAVES
 
 config TARGET_SPEAR320
 	bool "Support spear320"
 	select CPU_ARM926EJS
 	select BOARD_EARLY_INIT_F
+	imply CMD_SAVES
 
 config TARGET_SPEAR600
 	bool "Support spear600"
 	select CPU_ARM926EJS
 	select BOARD_EARLY_INIT_F
+	imply CMD_SAVES
 
 config TARGET_STV0991
 	bool "Support stv0991"
@@ -575,6 +580,7 @@
 	select CMD_POWEROFF
 	imply CMD_MTDPARTS
 	imply FIT
+	imply CMD_SAVES
 
 config ARCH_OMAP2PLUS
 	bool "TI OMAP2+"