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/netgear_dgnd3700v2_ram_defconfig b/configs/netgear_dgnd3700v2_ram_defconfig
index f7961ec..aa8af0b 100644
--- a/configs/netgear_dgnd3700v2_ram_defconfig
+++ b/configs/netgear_dgnd3700v2_ram_defconfig
@@ -31,6 +31,7 @@
 CONFIG_CMD_PING=y
 # CONFIG_CMD_MISC is not set
 CONFIG_DEFAULT_DEVICE_TREE="netgear,dgnd3700v2"
+CONFIG_SYS_RELOC_GD_ENV_ADDR=y
 CONFIG_NET_RANDOM_ETHADDR=y
 # CONFIG_DM_DEVICE_REMOVE is not set
 CONFIG_BCM6348_IUDMA=y