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/topic_miamiplus_defconfig b/configs/topic_miamiplus_defconfig
index 3092da4..af58d70 100644
--- a/configs/topic_miamiplus_defconfig
+++ b/configs/topic_miamiplus_defconfig
@@ -31,6 +31,7 @@
 CONFIG_CMD_CACHE=y
 CONFIG_OF_EMBED=y
 CONFIG_DEFAULT_DEVICE_TREE="zynq-topic-miamiplus"
+CONFIG_SYS_RELOC_GD_ENV_ADDR=y
 CONFIG_SPL_DM_SEQ_ALIAS=y
 CONFIG_DFU_RAM=y
 CONFIG_FPGA_XILINX=y