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/configs/gplugd_defconfig b/configs/gplugd_defconfig
index 4766be0..b27c109 100644
--- a/configs/gplugd_defconfig
+++ b/configs/gplugd_defconfig
@@ -18,6 +18,7 @@
 CONFIG_CMD_EXT2=y
 CONFIG_CMD_FAT=y
 CONFIG_ISO_PARTITION=y
+CONFIG_SYS_RELOC_GD_ENV_ADDR=y
 # CONFIG_MMC is not set
 CONFIG_MII=y
 CONFIG_SYS_NS16550=y