env: Add CONFIG_SYS_RELOC_GD_ENV_ADDR symbol

Today in initr_reloc_global_data() we use some non-obvious tests to
determine if we need to relocate the env_addr within gd or not.  In
order to facilitate migration of other symbols to Kconfig we need to
introduce a new symbol for this particular use case.

Cc: Wolfgang Denk <wd@denx.de>
Cc: Joe Hershberger <joe.hershberger@ni.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/env/Kconfig b/env/Kconfig
index 090cc79..3377870 100644
--- a/env/Kconfig
+++ b/env/Kconfig
@@ -535,6 +535,12 @@
 
 endif
 
+config SYS_RELOC_GD_ENV_ADDR
+	bool "Relocate gd->en_addr"
+	help
+	  Relocate the early env_addr pointer so we know it is not inside
+	  the binary. Some systems need this and for the rest, it doesn't hurt.
+
 config USE_DEFAULT_ENV_FILE
 	bool "Create default environment from file"
 	help