Convert CONFIG_SYS_MEM_TOP_HIDE to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_MEM_TOP_HIDE

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/origen_defconfig b/configs/origen_defconfig
index 6ffec86..b4b0d8b 100644
--- a/configs/origen_defconfig
+++ b/configs/origen_defconfig
@@ -16,6 +16,7 @@
 CONFIG_IDENT_STRING=" for ORIGEN"
 CONFIG_SYS_LOAD_ADDR=0x43e00000
 CONFIG_DISTRO_DEFAULTS=y
+CONFIG_SYS_MEM_TOP_HIDE=0x100000
 CONFIG_BOOTCOMMAND="if mmc rescan; then echo SD/MMC found on device ${mmcdev};if run loadbootenv; then echo Loaded environment from ${bootenv};run importbootenv;fi;if test -n $uenvcmd; then echo Running uenvcmd ...;run uenvcmd;fi;if run loadbootscript; then run bootscript; fi; fi;load mmc ${mmcdev} ${loadaddr} uImage; bootm ${loadaddr} "
 CONFIG_SYS_CONSOLE_IS_IN_ENV=y
 CONFIG_SYS_CONSOLE_INFO_QUIET=y