Convert CONFIG_CMD_ECCTEST to Kconfig

This converts the following to Kconfig:
   CONFIG_CMD_ECCTEST

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/powerpc/cpu/ppc4xx/Kconfig b/arch/powerpc/cpu/ppc4xx/Kconfig
index 38121c1..77e8fd4 100644
--- a/arch/powerpc/cpu/ppc4xx/Kconfig
+++ b/arch/powerpc/cpu/ppc4xx/Kconfig
@@ -137,6 +137,12 @@
 	  and control the CPU and peripehrals clocks. The programmed
 	  configuration is then used when the board boots.
 
+config CMD_ECCTEST
+	bool "Enable the 'ecctest' command"
+	help
+	  This command tests memory ECC by single and double error bit
+	  injection.
+
 source "board/amcc/acadia/Kconfig"
 source "board/amcc/bamboo/Kconfig"
 source "board/amcc/bubinga/Kconfig"