Convert CONFIG_CMD_ERRATA to Kconfig

This converts the following to Kconfig:
   CONFIG_CMD_ERRATA

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/powerpc/cpu/mpc85xx/Kconfig b/arch/powerpc/cpu/mpc85xx/Kconfig
index a87430c..88d56a9 100644
--- a/arch/powerpc/cpu/mpc85xx/Kconfig
+++ b/arch/powerpc/cpu/mpc85xx/Kconfig
@@ -4,6 +4,14 @@
 config SYS_CPU
 	default "mpc85xx"
 
+config CMD_ERRATA
+	bool "Enable the 'errata' command"
+	depends on MPC85xx
+	default y
+	help
+	  This enables the 'errata' command which displays a list of errata
+	  work-arounds which are enabled for the current board.
+
 choice
 	prompt "Target select"
 	optional